crypto: ccp - Add AMD Seamless Firmware Servicing (SFS) driver

From: Ashish Kalra <[email protected]>

When leaking certain page types, such as Hypervisor Fixed (HV_FIXED) pages, it does not make sense to dump RMP contents for the 2MB range of the page(s) being leaked. In the case of HV_FIXED pages, this is not an error situation where the surrounding 2MB page RMP entries can provide debug information.

Add new __snp_leak_pages() API with dump_rmp bool parameter to support continue adding pages to the snp_leaked_pages_list but not issue dump_rmpentry().

Make snp_leak_pages() a wrapper for the common case which also allows existing users to continue to dump RMP entries.

Suggested-by Thomas Lendacky <[email protected]>

Suggested-by Sean Christopherson <[email protected]>

Signed-off-by Ashish Kalra <[email protected]>

---
 arch/x86/include/asm/sev.h | 8 +++++++-
 arch/x86/virt/svm/sev.c    | 7 ++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

arch/x86/include/asm/sev.h +7 -1

index 00475b814ac4..7a1ae990b15f 100644
@@ -635,10 +635,15 @@ void snp_dump_hva_rmpentry(unsigned long address);
 int psmash(u64 pfn);
 int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immutable);
 int rmp_make_shared(u64 pfn, enum pg_level level);
-void snp_leak_pages(u64 pfn, unsigned int npages);
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp);
 void kdump_sev_callback(void);
 void snp_fixup_e820_tables(void);
 
+static inline void snp_leak_pages(u64 pfn, unsigned int pages)
+{
+	__snp_leak_pages(pfn, pages, true);
+}
+
 static inline void sev_evict_cache(void *va, int npages)
 {
 	volatile u8 val __always_unused;

@@ -668,6 +673,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 as
 	return -ENODEV;
 }
 static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; }
+static inline void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp) {}
 static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}
 static inline void kdump_sev_callback(void) { }
 static inline void snp_fixup_e820_tables(void) {}

arch/x86/virt/svm/sev.c +4 -3

index 942372e69b4d..ee643a6cd691 100644
@@ -1029,7 +1029,7 @@ int rmp_make_shared(u64 pfn, enum pg_level level)
 }
 EXPORT_SYMBOL_GPL(rmp_make_shared);
 
-void snp_leak_pages(u64 pfn, unsigned int npages)
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp)
 {
 	struct page *page = pfn_to_page(pfn);
 

@@ -1052,14 +1052,15 @@ void snp_leak_pages(u64 pfn, unsigned int npages)
 		    (PageHead(page) && compound_nr(page) <= npages))
 			list_add_tail(&page->buddy_list, &snp_leaked_pages_list);
 
-		dump_rmpentry(pfn);
+		if (dump_rmp)
+			dump_rmpentry(pfn);
 		snp_nr_leaked_pages++;
 		pfn++;
 		page++;
 	}
 	spin_unlock(&snp_leaked_pages_list_lock);
 }
-EXPORT_SYMBOL_GPL(snp_leak_pages);
+EXPORT_SYMBOL_GPL(__snp_leak_pages);
 
 void kdump_sev_callback(void)
 {

From: Ashish Kalra <[email protected]>

When leaking certain page types, such as Hypervisor Fixed (HV_FIXED) pages, it does not make sense to dump RMP contents for the 2MB range of the page(s) being leaked. In the case of HV_FIXED pages, this is not an error situation where the surrounding 2MB page RMP entries can provide debug information.

Add new __snp_leak_pages() API with dump_rmp bool parameter to support continue adding pages to the snp_leaked_pages_list but not issue dump_rmpentry().

Make snp_leak_pages() a wrapper for the common case which also allows existing users to continue to dump RMP entries.

Suggested-by Thomas Lendacky <[email protected]>

Suggested-by Sean Christopherson <[email protected]>

Signed-off-by Ashish Kalra <[email protected]>

---
 arch/x86/include/asm/sev.h | 8 +++++++-
 arch/x86/virt/svm/sev.c    | 7 ++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

Quoted 15 lines · Ashish Kalra

From: Ashish Kalra <[email protected]>

When leaking certain page types, such as Hypervisor Fixed (HV_FIXED) pages, it does not make sense to dump RMP contents for the 2MB range of the page(s) being leaked. In the case of HV_FIXED pages, this is not an error situation where the surrounding 2MB page RMP entries can provide debug information.

Add new __snp_leak_pages() API with dump_rmp bool parameter to support continue adding pages to the snp_leaked_pages_list but not issue dump_rmpentry().

Make snp_leak_pages() a wrapper for the common case which also allows existing users to continue to dump RMP entries.

Quoted 7 lines

Suggested-by Thomas Lendacky <[email protected]>

Suggested-by Sean Christopherson <[email protected]>

Signed-off-by Ashish Kalra <[email protected]>

---
 arch/x86/include/asm/sev.h | 8 +++++++-
 arch/x86/virt/svm/sev.c    | 7 ++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

Sean, lemme know if I should carry this through tip.

Quoted 24 lines · Borislav Petkov

Quoted 22 lines · Ashish Kalra

From: Ashish Kalra <[email protected]>

When leaking certain page types, such as Hypervisor Fixed (HV_FIXED) pages, it does not make sense to dump RMP contents for the 2MB range of the page(s) being leaked. In the case of HV_FIXED pages, this is not an error situation where the surrounding 2MB page RMP entries can provide debug information.

Add new __snp_leak_pages() API with dump_rmp bool parameter to support continue adding pages to the snp_leaked_pages_list but not issue dump_rmpentry().

Make snp_leak_pages() a wrapper for the common case which also allows existing users to continue to dump RMP entries.

Suggested-by Thomas Lendacky <[email protected]>

Suggested-by Sean Christopherson <[email protected]>

Signed-off-by Ashish Kalra <[email protected]>

---
 arch/x86/include/asm/sev.h | 8 +++++++-
 arch/x86/virt/svm/sev.c    | 7 ++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

Quoted 1 line

Sean, lemme know if I should carry this through tip.

Take them through tip, but the stubs mess in sev.h really needs to be cleaned up (doesn't have to block this series, but should be done sooner than later).

Right, I guess Tom's on that one...

As to the other two:

https://lore.kernel.org/r/e7807012187bdda8d76ab408b87f15631461993d.1757543774.git.ashish.kalra@amd.com
https://lore.kernel.org/r/7be1accd4c0968fe04d6efe6ebb0185d77bed129.1757543774.git.ashish.kalra@amd.com

Herbert, how do you want to proceed here?

Do you want me to give you an immutable branch with the first patch and you can base the other two ontop or should I carry all three through tip?

Yeah, it is time for patch tetris again... :-P

You can take those two patches directly with my ack:

Acked-by Herbert Xu <[email protected]>

arch/x86/include/asm/sev.h +6 -1

index 00475b814ac4..7a1ae990b15f 100644
@@ -635,10 +635,15 @@ void snp_dump_hva_rmpentry(unsigned long address);
 int psmash(u64 pfn);
 int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immutable);
 int rmp_make_shared(u64 pfn, enum pg_level level);
-void snp_leak_pages(u64 pfn, unsigned int npages);
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp);
 void kdump_sev_callback(void);
 void snp_fixup_e820_tables(void);
 
+static inline void snp_leak_pages(u64 pfn, unsigned int pages)
+{
+	__snp_leak_pages(pfn, pages, true);
+}
+
 static inline void sev_evict_cache(void *va, int npages)
 {
 	volatile u8 val __always_unused;

Quoted 22 lines · Ashish Kalra

arch/x86/include/asm/sev.h +6 -1

index 00475b814ac4..7a1ae990b15f 100644
@@ -635,10 +635,15 @@ void snp_dump_hva_rmpentry(unsigned long address);
 int psmash(u64 pfn);
 int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immutable);
 int rmp_make_shared(u64 pfn, enum pg_level level);
-void snp_leak_pages(u64 pfn, unsigned int npages);
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp);
 void kdump_sev_callback(void);
 void snp_fixup_e820_tables(void);
 
+static inline void snp_leak_pages(u64 pfn, unsigned int pages)
+{
+	__snp_leak_pages(pfn, pages, true);
+}
+
 static inline void sev_evict_cache(void *va, int npages)
 {
 	volatile u8 val __always_unused;

arch/x86/include/asm/sev.h static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 as · line 676

Quoted 4 lines

arch/x86/include/asm/sev.h +1 -0

@@ -668,6 +673,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 as
 	return -ENODEV;
 }
 static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; }
+static inline void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp) {}

This stub is unnecessary. As pointed out elsewhere[*], I'm pretty sure all these stubs are unnecessary.

Oof. Even worse, the stubs appear to be actively hiding bugs. The APIs are guarded with CONFIG_KVM_AMD_SEV=y, but **KVM** doesn't call any of these outside of SEV code. I.e. if *KVM* were the only user, the stubs would just be dead code.

But the below build failures show that they aren't dead code, which means that kernels with CONFIG_KVM_AMD_SEV=n will silently (until something explodes) do the wrong thing, because the stubs are hiding the missing dependencies.

arch/x86/boot/startup/sev-shared.c: In function ‘pvalidate_4k_page’:
arch/x86/boot/startup/sev-shared.c:820:17: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
820 | sev_evict_cache((void *)vaddr, 1);

      |                 ^~~~~~~~~~~~~~~
  AR      arch/x86/realmode/built-in.a
arch/x86/coco/sev/core.c: In function ‘pvalidate_pages’:
arch/x86/coco/sev/core.c:386:25: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
  386 |                         sev_evict_cache(pfn_to_kaddr(e->gfn), e->pagesize ? 512 : 1);
      |                         ^~~~~~~~~~~~~~~

arch/x86/mm/mem_encrypt.c: In function ‘mem_encrypt_setup_arch’:
arch/x86/mm/mem_encrypt.c:112:17: error: implicit declaration of function ‘snp_fixup_e820_tables’ [-Wimplicit-function-declaration]
112 | snp_fixup_e820_tables();

      |                 ^~~~~~~~~~~~~~~~~~~~~

arch/x86/mm/fault.c: In function ‘show_fault_oops’:
arch/x86/mm/fault.c:587:17: error: implicit declaration of function ‘snp_dump_hva_rmpentry’ [-Wimplicit-function-declaration]
587 | snp_dump_hva_rmpentry(address);

      |                 ^~~~~~~~~~~~~~~~~~~~~

arch/x86/kernel/cpu/amd.c: In function ‘bsp_determine_snp’:
arch/x86/kernel/cpu/amd.c:370:21: error: implicit declaration of function ‘snp_probe_rmptable_info’ [-Wimplicit-function-declaration]
370 | snp_probe_rmptable_info()) {

      |                     ^~~~~~~~~~~~~~~~~~~~~~~
  AR      drivers/iommu/amd/built-in.a
  AR      drivers/iommu/built-in.a
  AR      drivers/built-in.a

[*] https://lore.kernel.org/all/[email protected]

Quoted 7 lines · Sean Christopherson

But the below build failures show that they aren't dead code, which means that kernels with CONFIG_KVM_AMD_SEV=n will silently (until something explodes) do the wrong thing, because the stubs are hiding the missing dependencies.

arch/x86/boot/startup/sev-shared.c: In function ‘pvalidate_4k_page’:
arch/x86/boot/startup/sev-shared.c:820:17: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
820 | sev_evict_cache((void *)vaddr, 1);

Yeah, this one is on me. sev_evict_cache() is guest code and should be under the CONFIG_AMD_MEM_ENCRYPT #ifdef.

Quoted 9 lines

      |                 ^~~~~~~~~~~~~~~
  AR      arch/x86/realmode/built-in.a
arch/x86/coco/sev/core.c: In function ‘pvalidate_pages’:
arch/x86/coco/sev/core.c:386:25: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
  386 |                         sev_evict_cache(pfn_to_kaddr(e->gfn), e->pagesize ? 512 : 1);
      |                         ^~~~~~~~~~~~~~~

arch/x86/mm/mem_encrypt.c: In function ‘mem_encrypt_setup_arch’:
arch/x86/mm/mem_encrypt.c:112:17: error: implicit declaration of function ‘snp_fixup_e820_tables’ [-Wimplicit-function-declaration]
112 | snp_fixup_e820_tables();

This function is only meant to be used if we're going to run SEV guests, so being guarded by CONFIG_KVM_AMD_SEV was on purpose. I'm just not sure why the stub didn't get used... or did you remove them?

Quoted 22 lines · Tom Lendacky

Quoted 7 lines · Sean Christopherson

But the below build failures show that they aren't dead code, which means that kernels with CONFIG_KVM_AMD_SEV=n will silently (until something explodes) do the wrong thing, because the stubs are hiding the missing dependencies.

arch/x86/boot/startup/sev-shared.c: In function ‘pvalidate_4k_page’:
arch/x86/boot/startup/sev-shared.c:820:17: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
820 | sev_evict_cache((void *)vaddr, 1);

Yeah, this one is on me. sev_evict_cache() is guest code and should be under the CONFIG_AMD_MEM_ENCRYPT #ifdef.

Quoted 9 lines

      |                 ^~~~~~~~~~~~~~~
  AR      arch/x86/realmode/built-in.a
arch/x86/coco/sev/core.c: In function ‘pvalidate_pages’:
arch/x86/coco/sev/core.c:386:25: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
  386 |                         sev_evict_cache(pfn_to_kaddr(e->gfn), e->pagesize ? 512 : 1);
      |                         ^~~~~~~~~~~~~~~

arch/x86/mm/mem_encrypt.c: In function ‘mem_encrypt_setup_arch’:
arch/x86/mm/mem_encrypt.c:112:17: error: implicit declaration of function ‘snp_fixup_e820_tables’ [-Wimplicit-function-declaration]
112 | snp_fixup_e820_tables();

Quoted 3 lines

This function is only meant to be used if we're going to run SEV guests, so being guarded by CONFIG_KVM_AMD_SEV was on purpose. I'm just not sure why the stub didn't get used... or did you remove them?

I removed all the stubs to see what would break (I was expecting nothing since all of KVM's accesses are gated by CONFIG_KVM_AMD_SEV).

From: Ashish Kalra <[email protected]>

When SEV-SNP is active, the TEE extended command header page and all output buffers for TEE extended commands (such as used by Seamless Firmware servicing support) must be in hypervisor-fixed state, assigned to the hypervisor and marked immutable in the RMP entrie(s).

Add a new generic SEV API interface to allocate/free hypervisor fixed pages which abstracts hypervisor fixed page allocation/free for PSP sub devices. The API internally uses SNP_INIT_EX to transition pages to HV-Fixed page state.

If SNP is not enabled then the allocator is simply a wrapper over alloc_pages() and __free_pages().

When the sub device free the pages, they are put on a free list and future allocation requests will try to re-use the freed pages from this list. But this list is not preserved across PSP driver load/unload hence this free/reuse support is only supported while PSP driver is loaded. As HV_FIXED page state is only changed at reboot, these pages are leaked as they cannot be returned back to the page allocator and then potentially allocated to guests, which will cause SEV-SNP guests to fail to start or terminate when accessing the HV_FIXED page.

Suggested-by Thomas Lendacky <[email protected]>

Signed-off-by Ashish Kalra <[email protected]>

---
 drivers/crypto/ccp/sev-dev.c | 182 +++++++++++++++++++++++++++++++++++
 drivers/crypto/ccp/sev-dev.h |   3 +
 2 files changed, 185 insertions(+)

drivers/crypto/ccp/sev-dev.c +182 -0

index 9e797cbdf038..2300673c6683 100644
@@ -83,6 +83,21 @@ MODULE_FIRMWARE("amd/amd_sev_fam19h_model1xh.sbin"); /* 4th gen EPYC */
 static bool psp_dead;
 static int psp_timeout;
 
+enum snp_hv_fixed_pages_state {
+	ALLOCATED,
+	HV_FIXED,
+};
+
+struct snp_hv_fixed_pages_entry {
+	struct list_head list;
+	struct page *page;
+	unsigned int order;
+	bool free;
+	enum snp_hv_fixed_pages_state page_state;
+};
+
+static LIST_HEAD(snp_hv_fixed_pages);
+
 /* Trusted Memory Region (TMR):
  *   The TMR is a 1MB area that must be 1MB aligned.  Use the page allocator
  *   to allocate the memory, which will return aligned memory for the specified

@@ -1158,6 +1173,165 @@ static int snp_get_platform_data(struct sev_device *sev, int *error)
 	return rc;
 }
 
+/* Hypervisor Fixed pages API interface */
+static void snp_hv_fixed_pages_state_update(struct sev_device *sev,
+					    enum snp_hv_fixed_pages_state page_state)
+{
+	struct snp_hv_fixed_pages_entry *entry;
+
+	/* List is protected by sev_cmd_mutex */
+	lockdep_assert_held(&sev_cmd_mutex);
+
+	if (list_empty(&snp_hv_fixed_pages))
+		return;
+
+	list_for_each_entry(entry, &snp_hv_fixed_pages, list)
+		entry->page_state = page_state;
+}
+
+/*
+ * Allocate HV_FIXED pages in 2MB aligned sizes to ensure the whole
+ * 2MB pages are marked as HV_FIXED.
+ */
+struct page *snp_alloc_hv_fixed_pages(unsigned int num_2mb_pages)
+{
+	struct psp_device *psp_master = psp_get_master_device();
+	struct snp_hv_fixed_pages_entry *entry;
+	struct sev_device *sev;
+	unsigned int order;
+	struct page *page;
+
+	if (!psp_master || !psp_master->sev_data)
+		return NULL;
+
+	sev = psp_master->sev_data;
+
+	order = get_order(PMD_SIZE * num_2mb_pages);
+
+	/*
+	 * SNP_INIT_EX is protected by sev_cmd_mutex, therefore this list
+	 * also needs to be protected using the same mutex.
+	 */
+	guard(mutex)(&sev_cmd_mutex);
+
+	/*
+	 * This API uses SNP_INIT_EX to transition allocated pages to HV_Fixed
+	 * page state, fail if SNP is already initialized.
+	 */
+	if (sev->snp_initialized)
+		return NULL;
+
+	/* Re-use freed pages that match the request */
+	list_for_each_entry(entry, &snp_hv_fixed_pages, list) {
+		/* Hypervisor fixed page allocator implements exact fit policy */
+		if (entry->order == order && entry->free) {
+			entry->free = false;
+			memset(page_address(entry->page), 0,
+			       (1 << entry->order) * PAGE_SIZE);
+			return entry->page;
+		}
+	}
+
+	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
+	if (!page)
+		return NULL;
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry) {
+		__free_pages(page, order);
+		return NULL;
+	}
+
+	entry->page = page;
+	entry->order = order;
+	list_add_tail(&entry->list, &snp_hv_fixed_pages);
+
+	return page;
+}
+
+void snp_free_hv_fixed_pages(struct page *page)
+{
+	struct psp_device *psp_master = psp_get_master_device();
+	struct snp_hv_fixed_pages_entry *entry, *nentry;
+
+	if (!psp_master || !psp_master->sev_data)
+		return;
+
+	/*
+	 * SNP_INIT_EX is protected by sev_cmd_mutex, therefore this list
+	 * also needs to be protected using the same mutex.
+	 */
+	guard(mutex)(&sev_cmd_mutex);
+
+	list_for_each_entry_safe(entry, nentry, &snp_hv_fixed_pages, list) {
+		if (entry->page != page)
+			continue;
+
+		/*
+		 * HV_FIXED page state cannot be changed until reboot
+		 * and they cannot be used by an SNP guest, so they cannot
+		 * be returned back to the page allocator.
+		 * Mark the pages as free internally to allow possible re-use.
+		 */
+		if (entry->page_state == HV_FIXED) {
+			entry->free = true;
+		} else {
+			__free_pages(page, entry->order);
+			list_del(&entry->list);
+			kfree(entry);
+		}
+		return;
+	}
+}
+
+static void snp_add_hv_fixed_pages(struct sev_device *sev, struct sev_data_range_list *range_list)
+{
+	struct snp_hv_fixed_pages_entry *entry;
+	struct sev_data_range *range;
+	int num_elements;
+
+	lockdep_assert_held(&sev_cmd_mutex);
+
+	if (list_empty(&snp_hv_fixed_pages))
+		return;
+
+	num_elements = list_count_nodes(&snp_hv_fixed_pages) +
+		       range_list->num_elements;
+
+	/*
+	 * Ensure the list of HV_FIXED pages that will be passed to firmware
+	 * do not exceed the page-sized argument buffer.
+	 */
+	if (num_elements * sizeof(*range) + sizeof(*range_list) > PAGE_SIZE) {
+		dev_warn(sev->dev, "Additional HV_Fixed pages cannot be accommodated, omitting\n");
+		return;
+	}
+
+	range = &range_list->ranges[range_list->num_elements];
+	list_for_each_entry(entry, &snp_hv_fixed_pages, list) {
+		range->base = page_to_pfn(entry->page) << PAGE_SHIFT;
+		range->page_count = 1 << entry->order;
+		range++;
+	}
+	range_list->num_elements = num_elements;
+}
+
+static void snp_leak_hv_fixed_pages(void)
+{
+	struct snp_hv_fixed_pages_entry *entry;
+
+	/* List is protected by sev_cmd_mutex */
+	lockdep_assert_held(&sev_cmd_mutex);
+
+	if (list_empty(&snp_hv_fixed_pages))
+		return;
+
+	list_for_each_entry(entry, &snp_hv_fixed_pages, list)
+		if (entry->page_state == HV_FIXED)
+			__snp_leak_pages(page_to_pfn(entry->page),
+					 1 << entry->order, false);
+}
+
 static int snp_filter_reserved_mem_regions(struct resource *rs, void *arg)
 {
 	struct sev_data_range_list *range_list = arg;

@@ -1248,6 +1422,12 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
 			return rc;
 		}
 
+		/*
+		 * Add HV_Fixed pages from other PSP sub-devices, such as SFS to the
+		 * HV_Fixed page list.
+		 */
+		snp_add_hv_fixed_pages(sev, snp_range_list);
+
 		memset(&data, 0, sizeof(data));
 
 		if (max_snp_asid) {

@@ -1293,6 +1473,7 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
 		return rc;
 	}
 
+	snp_hv_fixed_pages_state_update(sev, HV_FIXED);
 	sev->snp_initialized = true;
 	dev_dbg(sev->dev, "SEV-SNP firmware initialized\n");
 

@@ -1896,6 +2077,7 @@ static int __sev_snp_shutdown_locked(int *error, bool panic)
 		return ret;
 	}
 
+	snp_leak_hv_fixed_pages();
 	sev->snp_initialized = false;
 	dev_dbg(sev->dev, "SEV-SNP firmware shutdown\n");
 

drivers/crypto/ccp/sev-dev.h +3 -0

index 5aed2595c9ae..ac03bd0848f7 100644
@@ -69,4 +69,7 @@ void sev_dev_destroy(struct psp_device *psp);
 void sev_pci_init(void);
 void sev_pci_exit(void);
 
+struct page *snp_alloc_hv_fixed_pages(unsigned int num_2mb_pages);
+void snp_free_hv_fixed_pages(struct page *page);
+
 #endif /* __SEV_DEV_H */

From: Ashish Kalra <[email protected]>

AMD Seamless Firmware Servicing (SFS) is a secure method to allow non-persistent updates to running firmware and settings without requiring BIOS reflash and/or system reset.

SFS does not address anything that runs on the x86 processors and it can be used to update ASP firmware, modules, register settings and update firmware for other microprocessors like TMPM, etc.

SFS driver support adds ioctl support to communicate the SFS commands to the ASP/PSP by using the TEE mailbox interface.

The Seamless Firmware Servicing (SFS) driver is added as a PSP sub-device.

For detailed information, please look at the SFS specifications:
https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/58604.pdf

Signed-off-by Ashish Kalra <[email protected]>

---
 drivers/crypto/ccp/Makefile         |   3 +-
 drivers/crypto/ccp/psp-dev.c        |  20 ++
 drivers/crypto/ccp/psp-dev.h        |   8 +-
 drivers/crypto/ccp/sfs.c            | 310 ++++++++++++++++++++++++++++
 drivers/crypto/ccp/sfs.h            |  47 +++++
 include/linux/psp-platform-access.h |   2 +
 include/uapi/linux/psp-sfs.h        |  87 ++++++++
 7 files changed, 475 insertions(+), 2 deletions(-)
 create mode 100644 drivers/crypto/ccp/sfs.c
 create mode 100644 drivers/crypto/ccp/sfs.h
 create mode 100644 include/uapi/linux/psp-sfs.h

drivers/crypto/ccp/Makefile +2 -1

index 394484929dae..a9626b30044a 100644
@@ -13,7 +13,8 @@ ccp-$(CONFIG_CRYPTO_DEV_SP_PSP) += psp-dev.o \
                                    tee-dev.o \
                                    platform-access.o \
                                    dbc.o \
-                                   hsti.o
+                                   hsti.o \
+                                   sfs.o
 
 obj-$(CONFIG_CRYPTO_DEV_CCP_CRYPTO) += ccp-crypto.o
 ccp-crypto-objs := ccp-crypto-main.o \

drivers/crypto/ccp/psp-dev.c +20 -0

index 1c5a7189631e..9e21da0e298a 100644
@@ -17,6 +17,7 @@
 #include "psp-dev.h"
 #include "sev-dev.h"
 #include "tee-dev.h"
+#include "sfs.h"
 #include "platform-access.h"
 #include "dbc.h"
 #include "hsti.h"

@@ -182,6 +183,17 @@ static int psp_check_tee_support(struct psp_device *psp)
 	return 0;
 }
 
+static int psp_check_sfs_support(struct psp_device *psp)
+{
+	/* Check if device supports SFS feature */
+	if (!psp->capability.sfs) {
+		dev_dbg(psp->dev, "psp does not support SFS\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static int psp_init(struct psp_device *psp)
 {
 	int ret;

@@ -198,6 +210,12 @@ static int psp_init(struct psp_device *psp)
 			return ret;
 	}
 
+	if (!psp_check_sfs_support(psp)) {
+		ret = sfs_dev_init(psp);
+		if (ret)
+			return ret;
+	}
+
 	if (psp->vdata->platform_access) {
 		ret = platform_access_dev_init(psp);
 		if (ret)

@@ -302,6 +320,8 @@ void psp_dev_destroy(struct sp_device *sp)
 
 	tee_dev_destroy(psp);
 
+	sfs_dev_destroy(psp);
+
 	dbc_dev_destroy(psp);
 
 	platform_access_dev_destroy(psp);

drivers/crypto/ccp/psp-dev.h +7 -1

index e43ce87ede76..268c83f298cb 100644
@@ -32,7 +32,8 @@ union psp_cap_register {
 		unsigned int sev			:1,
 			     tee			:1,
 			     dbc_thru_ext		:1,
-			     rsvd1			:4,
+			     sfs			:1,
+			     rsvd1			:3,
 			     security_reporting		:1,
 			     fused_part			:1,
 			     rsvd2			:1,

@@ -68,6 +69,7 @@ struct psp_device {
 	void *tee_data;
 	void *platform_access_data;
 	void *dbc_data;
+	void *sfs_data;
 
 	union psp_cap_register capability;
 };

@@ -118,12 +120,16 @@ struct psp_ext_request {
  * @PSP_SUB_CMD_DBC_SET_UID:		Set UID for DBC
  * @PSP_SUB_CMD_DBC_GET_PARAMETER:	Get parameter from DBC
  * @PSP_SUB_CMD_DBC_SET_PARAMETER:	Set parameter for DBC
+ * @PSP_SUB_CMD_SFS_GET_FW_VERS:	Get firmware versions for ASP and other MP
+ * @PSP_SUB_CMD_SFS_UPDATE:		Command to load, verify and execute SFS package
  */
 enum psp_sub_cmd {
 	PSP_SUB_CMD_DBC_GET_NONCE	= PSP_DYNAMIC_BOOST_GET_NONCE,
 	PSP_SUB_CMD_DBC_SET_UID		= PSP_DYNAMIC_BOOST_SET_UID,
 	PSP_SUB_CMD_DBC_GET_PARAMETER	= PSP_DYNAMIC_BOOST_GET_PARAMETER,
 	PSP_SUB_CMD_DBC_SET_PARAMETER	= PSP_DYNAMIC_BOOST_SET_PARAMETER,
+	PSP_SUB_CMD_SFS_GET_FW_VERS	= PSP_SFS_GET_FW_VERSIONS,
+	PSP_SUB_CMD_SFS_UPDATE		= PSP_SFS_UPDATE,
 };
 
 int psp_extended_mailbox_cmd(struct psp_device *psp, unsigned int timeout_msecs,

drivers/crypto/ccp/sfs.c new file +61 -0

new file mode 100644
index 000000000000..d56412f24669
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Secure Processor Seamless Firmware Servicing support.
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ *
+ * Author: Ashish Kalra <[email protected]>
+ */
+
+#include <linux/firmware.h>
+
+#include "sfs.h"
+#include "sev-dev.h"
+
+#define SFS_DEFAULT_TIMEOUT		(10 * MSEC_PER_SEC)
+#define SFS_MAX_PAYLOAD_SIZE		(2 * 1024 * 1024)
+#define SFS_NUM_2MB_PAGES_CMDBUF	(SFS_MAX_PAYLOAD_SIZE / PMD_SIZE)
+#define SFS_NUM_PAGES_CMDBUF		(SFS_MAX_PAYLOAD_SIZE / PAGE_SIZE)
+
+static DEFINE_MUTEX(sfs_ioctl_mutex);
+
+static struct sfs_misc_dev *misc_dev;
+
+static int send_sfs_cmd(struct sfs_device *sfs_dev, int msg)
+{
+	int ret;
+
+	sfs_dev->command_buf->hdr.status = 0;
+	sfs_dev->command_buf->hdr.sub_cmd_id = msg;
+
+	ret = psp_extended_mailbox_cmd(sfs_dev->psp,
+				       SFS_DEFAULT_TIMEOUT,
+				       (struct psp_ext_request *)sfs_dev->command_buf);
+	if (ret == -EIO) {
+		dev_dbg(sfs_dev->dev,
+			 "msg 0x%x failed with PSP error: 0x%x, extended status: 0x%x\n",
+			 msg, sfs_dev->command_buf->hdr.status,
+			 *(u32 *)sfs_dev->command_buf->buf);
+	}
+
+	return ret;
+}
+
+static int send_sfs_get_fw_versions(struct sfs_device *sfs_dev)
+{
+	/*
+	 * SFS_GET_FW_VERSIONS command needs the output buffer to be
+	 * initialized to 0xC7 in every byte.
+	 */
+	memset(sfs_dev->command_buf->sfs_buffer, 0xc7, PAGE_SIZE);
+	sfs_dev->command_buf->hdr.payload_size = 2 * PAGE_SIZE;
+
+	return send_sfs_cmd(sfs_dev, PSP_SFS_GET_FW_VERSIONS);
+}
+
+static int send_sfs_update_package(struct sfs_device *sfs_dev, const char *payload_name)
+{
+	char payload_path[PAYLOAD_NAME_SIZE + sizeof("amd/")];
+	const struct firmware *firmware;
+	unsigned long package_size;
+	int ret;

drivers/crypto/ccp/sfs.c new file +239 -0

+		return -ENOENT;
+	}
+
+	/*
+	 * SFS Update Package command's input buffer contains TEE_EXT_CMD_BUFFER
+	 * followed by the Update Package and it should be 64KB aligned.
+	 */
+	package_size = ALIGN(firmware->size + PAGE_SIZE, 0x10000U);
+
+	/*
+	 * SFS command buffer is a pre-allocated 2MB buffer, fail update package
+	 * if SFS payload is larger than the pre-allocated command buffer.
+	 */
+	if (package_size > SFS_MAX_PAYLOAD_SIZE) {
+		dev_warn(sfs_dev->dev,
+			 "SFS payload size %ld larger than maximum supported payload size of %u\n",
+			 package_size, SFS_MAX_PAYLOAD_SIZE);
+		release_firmware(firmware);
+		return -E2BIG;
+	}
+
+	/*
+	 * Copy firmware data to a HV_Fixed memory region.
+	 */
+	memcpy(sfs_dev->command_buf->sfs_buffer, firmware->data, firmware->size);
+	sfs_dev->command_buf->hdr.payload_size = package_size;
+
+	release_firmware(firmware);
+
+	return send_sfs_cmd(sfs_dev, PSP_SFS_UPDATE);
+}
+
+static long sfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct sfs_user_get_fw_versions __user *sfs_get_fw_versions;
+	struct sfs_user_update_package __user *sfs_update_package;
+	struct psp_device *psp_master = psp_get_master_device();
+	char payload_name[PAYLOAD_NAME_SIZE];
+	struct sfs_device *sfs_dev;
+	int ret = 0;
+
+	if (!psp_master || !psp_master->sfs_data)
+		return -ENODEV;
+
+	sfs_dev = psp_master->sfs_data;
+
+	guard(mutex)(&sfs_ioctl_mutex);
+
+	switch (cmd) {
+	case SFSIOCFWVERS:
+		dev_dbg(sfs_dev->dev, "in SFSIOCFWVERS\n");
+
+		sfs_get_fw_versions = (struct sfs_user_get_fw_versions __user *)arg;
+
+		ret = send_sfs_get_fw_versions(sfs_dev);
+		if (ret && ret != -EIO)
+			return ret;
+
+		/*
+		 * Return SFS status and extended status back to userspace
+		 * if PSP status indicated success or command error.
+		 */
+		if (copy_to_user(&sfs_get_fw_versions->blob, sfs_dev->command_buf->sfs_buffer,
+				 PAGE_SIZE))
+			return -EFAULT;
+		if (copy_to_user(&sfs_get_fw_versions->sfs_status,
+				 &sfs_dev->command_buf->hdr.status,
+				 sizeof(sfs_get_fw_versions->sfs_status)))
+			return -EFAULT;
+		if (copy_to_user(&sfs_get_fw_versions->sfs_extended_status,
+				 &sfs_dev->command_buf->buf,
+				 sizeof(sfs_get_fw_versions->sfs_extended_status)))
+			return -EFAULT;
+		break;
+	case SFSIOCUPDATEPKG:
+		dev_dbg(sfs_dev->dev, "in SFSIOCUPDATEPKG\n");
+
+		sfs_update_package = (struct sfs_user_update_package __user *)arg;
+
+		if (copy_from_user(payload_name, sfs_update_package->payload_name,
+				   PAYLOAD_NAME_SIZE))
+			return -EFAULT;
+
+		ret = send_sfs_update_package(sfs_dev, payload_name);
+		if (ret && ret != -EIO)
+			return ret;
+
+		/*
+		 * Return SFS status and extended status back to userspace
+		 * if PSP status indicated success or command error.
+		 */
+		if (copy_to_user(&sfs_update_package->sfs_status,
+				 &sfs_dev->command_buf->hdr.status,
+				 sizeof(sfs_update_package->sfs_status)))
+			return -EFAULT;
+		if (copy_to_user(&sfs_update_package->sfs_extended_status,
+				 &sfs_dev->command_buf->buf,
+				 sizeof(sfs_update_package->sfs_extended_status)))
+			return -EFAULT;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static const struct file_operations sfs_fops = {
+	.owner	= THIS_MODULE,
+	.unlocked_ioctl = sfs_ioctl,
+};
+
+static void sfs_exit(struct kref *ref)
+{
+	misc_deregister(&misc_dev->misc);
+	kfree(misc_dev);
+	misc_dev = NULL;
+}
+
+void sfs_dev_destroy(struct psp_device *psp)
+{
+	struct sfs_device *sfs_dev = psp->sfs_data;
+
+	if (!sfs_dev)
+		return;
+
+	/*
+	 * Change SFS command buffer back to the default "Write-Back" type.
+	 */
+	set_memory_wb((unsigned long)sfs_dev->command_buf, SFS_NUM_PAGES_CMDBUF);
+
+	snp_free_hv_fixed_pages(sfs_dev->page);
+
+	if (sfs_dev->misc)
+		kref_put(&misc_dev->refcount, sfs_exit);
+
+	psp->sfs_data = NULL;
+}
+
+/* Based on sev_misc_init() */
+static int sfs_misc_init(struct sfs_device *sfs)
+{
+	struct device *dev = sfs->dev;
+	int ret;
+
+	/*
+	 * SFS feature support can be detected on multiple devices but the SFS
+	 * FW commands must be issued on the master. During probe, we do not
+	 * know the master hence we create /dev/sfs on the first device probe.
+	 */
+	if (!misc_dev) {
+		struct miscdevice *misc;
+
+		misc_dev = kzalloc(sizeof(*misc_dev), GFP_KERNEL);
+		if (!misc_dev)
+			return -ENOMEM;
+
+		misc = &misc_dev->misc;
+		misc->minor = MISC_DYNAMIC_MINOR;
+		misc->name = "sfs";
+		misc->fops = &sfs_fops;
+		misc->mode = 0600;
+
+		ret = misc_register(misc);
+		if (ret)
+			return ret;
+
+		kref_init(&misc_dev->refcount);
+	} else {
+		kref_get(&misc_dev->refcount);
+	}
+
+	sfs->misc = misc_dev;
+	dev_dbg(dev, "registered SFS device\n");
+
+	return 0;
+}
+
+int sfs_dev_init(struct psp_device *psp)
+{
+	struct device *dev = psp->dev;
+	struct sfs_device *sfs_dev;
+	struct page *page;
+	int ret = -ENOMEM;
+
+	sfs_dev = devm_kzalloc(dev, sizeof(*sfs_dev), GFP_KERNEL);
+	if (!sfs_dev)
+		return -ENOMEM;
+
+	/*
+	 * Pre-allocate 2MB command buffer for all SFS commands using
+	 * SNP HV_Fixed page allocator which also transitions the
+	 * SFS command buffer to HV_Fixed page state if SNP is enabled.
+	 */
+	page = snp_alloc_hv_fixed_pages(SFS_NUM_2MB_PAGES_CMDBUF);
+	if (!page) {
+		dev_dbg(dev, "Command Buffer HV-Fixed page allocation failed\n");
+		goto cleanup_dev;
+	}
+	sfs_dev->page = page;
+	sfs_dev->command_buf = page_address(page);
+
+	dev_dbg(dev, "Command buffer 0x%px to be marked as HV_Fixed\n", sfs_dev->command_buf);
+
+	/*
+	 * SFS command buffer must be mapped as non-cacheable.
+	 */
+	ret = set_memory_uc((unsigned long)sfs_dev->command_buf, SFS_NUM_PAGES_CMDBUF);
+	if (ret) {
+		dev_dbg(dev, "Set memory uc failed\n");
+		goto cleanup_cmd_buf;
+	}
+
+	dev_dbg(dev, "Command buffer 0x%px marked uncacheable\n", sfs_dev->command_buf);
+
+	psp->sfs_data = sfs_dev;
+	sfs_dev->dev = dev;
+	sfs_dev->psp = psp;
+
+	ret = sfs_misc_init(sfs_dev);
+	if (ret)
+		goto cleanup_mem_attr;
+
+	dev_notice(sfs_dev->dev, "SFS support is available\n");
+
+	return 0;
+
+cleanup_mem_attr:
+	set_memory_wb((unsigned long)sfs_dev->command_buf, SFS_NUM_PAGES_CMDBUF);
+
+cleanup_cmd_buf:
+	snp_free_hv_fixed_pages(page);
+
+cleanup_dev:
+	psp->sfs_data = NULL;
+	devm_kfree(dev, sfs_dev);
+
+	return ret;
+}

drivers/crypto/ccp/sfs.h new file +47 -0

new file mode 100644
index 000000000000..97704c210efd
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * AMD Platform Security Processor (PSP) Seamless Firmware (SFS) Support.
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ *
+ * Author: Ashish Kalra <[email protected]>
+ */
+
+#ifndef __SFS_H__
+#define __SFS_H__
+
+#include <uapi/linux/psp-sfs.h>
+
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/psp-sev.h>
+#include <linux/psp-platform-access.h>
+#include <linux/set_memory.h>
+
+#include "psp-dev.h"
+
+struct sfs_misc_dev {
+	struct kref refcount;
+	struct miscdevice misc;
+};
+
+struct sfs_command {
+	struct psp_ext_req_buffer_hdr hdr;
+	u8 buf[PAGE_SIZE - sizeof(struct psp_ext_req_buffer_hdr)];
+	u8 sfs_buffer[];
+} __packed;
+
+struct sfs_device {
+	struct device *dev;
+	struct psp_device *psp;
+
+	struct page *page;
+	struct sfs_command *command_buf;
+
+	struct sfs_misc_dev *misc;
+};
+
+void sfs_dev_destroy(struct psp_device *psp);
+int sfs_dev_init(struct psp_device *psp);
+
+#endif /* __SFS_H__ */

include/linux/psp-platform-access.h +2 -0

index 1504fb012c05..540abf7de048 100644
@@ -7,6 +7,8 @@
 
 enum psp_platform_access_msg {
 	PSP_CMD_NONE			= 0x0,
+	PSP_SFS_GET_FW_VERSIONS,
+	PSP_SFS_UPDATE,
 	PSP_CMD_HSTI_QUERY		= 0x14,
 	PSP_I2C_REQ_BUS_CMD		= 0x64,
 	PSP_DYNAMIC_BOOST_GET_NONCE,

include/uapi/linux/psp-sfs.h new file +87 -0

new file mode 100644
index 000000000000..94e51670383c
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+ * Userspace interface for AMD Seamless Firmware Servicing (SFS)
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ *
+ * Author: Ashish Kalra <[email protected]>
+ */
+
+#ifndef __PSP_SFS_USER_H__
+#define __PSP_SFS_USER_H__
+
+#include <linux/types.h>
+
+/**
+ * SFS: AMD Seamless Firmware Support (SFS) interface
+ */
+
+#define PAYLOAD_NAME_SIZE	64
+#define TEE_EXT_CMD_BUFFER_SIZE	4096
+
+/**
+ * struct sfs_user_get_fw_versions - get current level of base firmware (output).
+ * @blob:                  current level of base firmware for ASP and patch levels (input/output).
+ * @sfs_status:            32-bit SFS status value (output).
+ * @sfs_extended_status:   32-bit SFS extended status value (output).
+ */
+struct sfs_user_get_fw_versions {
+	__u8	blob[TEE_EXT_CMD_BUFFER_SIZE];
+	__u32	sfs_status;
+	__u32	sfs_extended_status;
+} __packed;
+
+/**
+ * struct sfs_user_update_package - update SFS package (input).
+ * @payload_name:          name of SFS package to load, verify and execute (input).
+ * @sfs_status:            32-bit SFS status value (output).
+ * @sfs_extended_status:   32-bit SFS extended status value (output).
+ */
+struct sfs_user_update_package {
+	char	payload_name[PAYLOAD_NAME_SIZE];
+	__u32	sfs_status;
+	__u32	sfs_extended_status;
+} __packed;
+
+/**
+ * Seamless Firmware Support (SFS) IOC
+ *
+ * possible return codes for all SFS IOCTLs:
+ *  0:          success
+ *  -EINVAL:    invalid input
+ *  -E2BIG:     excess data passed
+ *  -EFAULT:    failed to copy to/from userspace
+ *  -EBUSY:     mailbox in recovery or in use
+ *  -ENODEV:    driver not bound with PSP device
+ *  -EACCES:    request isn't authorized
+ *  -EINVAL:    invalid parameter
+ *  -ETIMEDOUT: request timed out
+ *  -EAGAIN:    invalid request for state machine
+ *  -ENOENT:    not implemented
+ *  -ENFILE:    overflow
+ *  -EPERM:     invalid signature
+ *  -EIO:       PSP I/O error
+ */
+#define SFS_IOC_TYPE	'S'
+
+/**
+ * SFSIOCFWVERS - returns blob containing FW versions
+ *                ASP provides the current level of Base Firmware for the ASP
+ *                and the other microprocessors as well as current patch
+ *                level(s).
+ */
+#define SFSIOCFWVERS	_IOWR(SFS_IOC_TYPE, 0x1, struct sfs_user_get_fw_versions)
+
+/**
+ * SFSIOCUPDATEPKG - updates package/payload
+ *                   ASP loads, verifies and executes the SFS package.
+ *                   By default, the SFS package/payload is loaded from
+ *                   /lib/firmware/amd, but alternative firmware loading
+ *                   path can be specified using kernel parameter
+ *                   firmware_class.path or the firmware loading path
+ *                   can be customized using sysfs file:
+ *                   /sys/module/firmware_class/parameters/path.
+ */
+#define SFSIOCUPDATEPKG	_IOWR(SFS_IOC_TYPE, 0x2, struct sfs_user_update_package)
+
+#endif /* __PSP_SFS_USER_H__ */