Export TDX module information via SYSFS

From: "Alexey Gladkov (Intel)" <[email protected]>

Expose the TDX module information to userspace. The version information is valuable for debugging, as knowing the exact module version can help reproduce TDX-related issues.

Signed-off-by Alexey Gladkov (Intel) <[email protected]>

---
 arch/x86/Kconfig                  |  1 +
 arch/x86/include/asm/shared/tdx.h |  2 +
 arch/x86/include/asm/tdx.h        | 12 +++++
 arch/x86/virt/vmx/tdx/tdx.c       | 74 +++++++++++++++++++++++++++++++
 4 files changed, 89 insertions(+)

arch/x86/Kconfig +1 -0

index be2c311f5118..516f3539d0c7 100644
@@ -1986,6 +1986,7 @@ config INTEL_TDX_HOST
 	depends on CONTIG_ALLOC
 	depends on !KEXEC_CORE
 	depends on X86_MCE
+	select SYS_HYPERVISOR
 	help
 	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
 	  host and certain physical attacks.  This option enables necessary TDX

arch/x86/include/asm/shared/tdx.h +2 -0

index 606d93a1cbac..92ee9dfb21e7 100644
@@ -18,6 +18,8 @@
 #define TDG_MEM_PAGE_ACCEPT		6
 #define TDG_VM_RD			7
 #define TDG_VM_WR			8
+/* TDG_SYS_RD is available since TDX module version 1.5 and later. */
+#define TDG_SYS_RD			11
 
 /* TDX attributes */
 #define TDX_ATTR_DEBUG_BIT		0

arch/x86/include/asm/tdx.h +12 -0

index e6b003fe7f5e..95d748bc8464 100644
@@ -31,6 +31,18 @@
 #define TDX_SUCCESS		0ULL
 #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
 
+/*
+ * TDX metadata base field id, used by TDCALL TDG.SYS.RD
+ * See TDX ABI Spec Global Metadata Fields
+ */
+#define TDX_SYS_MINOR_FID		0x0800000100000003ULL
+#define TDX_SYS_MAJOR_FID		0x0800000100000004ULL
+#define TDX_SYS_UPDATE_FID		0x0800000100000005ULL
+#define TDX_SYS_INTERNAL_FID		0x0800000100000006ULL
+#define TDX_SYS_BUILD_DATE_FID		0x8800000200000001ULL
+#define TDX_SYS_BUILD_NUM_FID		0x8800000100000002ULL
+#define TDX_SYS_FEATURES0_FID		0x0A00000300000008ULL
+
 #ifndef __ASSEMBLY__
 
 #include <uapi/asm/mce.h>

arch/x86/virt/vmx/tdx/tdx.c +42 -0

index f5e2a937c1e7..89378e2a1f66 100644
@@ -1869,3 +1869,77 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
 	return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
 }
 EXPORT_SYMBOL_GPL(tdh_phymem_page_wbinvd_hkid);
+
+#ifdef CONFIG_SYSFS
+#define TDX_SYSFS_ATTR(_field, _name, fmt)				\
+static ssize_t _name ## _show(						\
+	struct kobject *kobj, struct kobj_attribute *attr, char *buf)	\
+{									\
+	u64 value = 0;							\
+	read_sys_metadata_field(_field, &value);			\
+	return sprintf(buf, fmt, value);				\
+}									\
+static struct kobj_attribute _name ## _attr = __ATTR_RO(_name)
+
+TDX_SYSFS_ATTR(TDX_SYS_MINOR_FID, minor, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_MAJOR_FID, major, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_UPDATE_FID, update, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_BUILD_NUM_FID, build_num, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_BUILD_DATE_FID, build_date, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_FEATURES0_FID, features0, "%llx\n");
+
+static struct attribute *version_attrs[] = {
+	&minor_attr.attr,
+	&major_attr.attr,
+	&update_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group version_attr_group = {
+	.name = "version",
+	.attrs = version_attrs,
+};
+
+static struct attribute *properties_attrs[] = {
+	&build_num_attr.attr,
+	&build_date_attr.attr,
+	&features0_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group properties_attr_group = {
+	.name = "properties",
+	.attrs = properties_attrs,
+};

Quoted 112 lines · Alexey Gladkov

From: "Alexey Gladkov (Intel)" <[email protected]>

Expose the TDX module information to userspace. The version information is valuable for debugging, as knowing the exact module version can help reproduce TDX-related issues.

Signed-off-by Alexey Gladkov (Intel) <[email protected]>

---
 arch/x86/Kconfig                  |  1 +
 arch/x86/include/asm/shared/tdx.h |  2 +
 arch/x86/include/asm/tdx.h        | 12 +++++
 arch/x86/virt/vmx/tdx/tdx.c       | 74 +++++++++++++++++++++++++++++++
 4 files changed, 89 insertions(+)

arch/x86/Kconfig +1 -0

index be2c311f5118..516f3539d0c7 100644
@@ -1986,6 +1986,7 @@ config INTEL_TDX_HOST
 	depends on CONTIG_ALLOC
 	depends on !KEXEC_CORE
 	depends on X86_MCE
+	select SYS_HYPERVISOR
 	help
 	  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
 	  host and certain physical attacks.  This option enables necessary TDX

arch/x86/include/asm/shared/tdx.h +2 -0

index 606d93a1cbac..92ee9dfb21e7 100644
@@ -18,6 +18,8 @@
 #define TDG_MEM_PAGE_ACCEPT		6
 #define TDG_VM_RD			7
 #define TDG_VM_WR			8
+/* TDG_SYS_RD is available since TDX module version 1.5 and later. */
+#define TDG_SYS_RD			11
 
 /* TDX attributes */
 #define TDX_ATTR_DEBUG_BIT		0

arch/x86/include/asm/tdx.h +12 -0

index e6b003fe7f5e..95d748bc8464 100644
@@ -31,6 +31,18 @@
 #define TDX_SUCCESS		0ULL
 #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
 
+/*
+ * TDX metadata base field id, used by TDCALL TDG.SYS.RD
+ * See TDX ABI Spec Global Metadata Fields
+ */
+#define TDX_SYS_MINOR_FID		0x0800000100000003ULL
+#define TDX_SYS_MAJOR_FID		0x0800000100000004ULL
+#define TDX_SYS_UPDATE_FID		0x0800000100000005ULL
+#define TDX_SYS_INTERNAL_FID		0x0800000100000006ULL
+#define TDX_SYS_BUILD_DATE_FID		0x8800000200000001ULL
+#define TDX_SYS_BUILD_NUM_FID		0x8800000100000002ULL
+#define TDX_SYS_FEATURES0_FID		0x0A00000300000008ULL
+
 #ifndef __ASSEMBLY__
 
 #include <uapi/asm/mce.h>

arch/x86/virt/vmx/tdx/tdx.c +42 -0

index f5e2a937c1e7..89378e2a1f66 100644
@@ -1869,3 +1869,77 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
 	return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
 }
 EXPORT_SYMBOL_GPL(tdh_phymem_page_wbinvd_hkid);
+
+#ifdef CONFIG_SYSFS
+#define TDX_SYSFS_ATTR(_field, _name, fmt)				\
+static ssize_t _name ## _show(						\
+	struct kobject *kobj, struct kobj_attribute *attr, char *buf)	\
+{									\
+	u64 value = 0;							\
+	read_sys_metadata_field(_field, &value);			\
+	return sprintf(buf, fmt, value);				\
+}									\
+static struct kobj_attribute _name ## _attr = __ATTR_RO(_name)
+
+TDX_SYSFS_ATTR(TDX_SYS_MINOR_FID, minor, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_MAJOR_FID, major, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_UPDATE_FID, update, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_BUILD_NUM_FID, build_num, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_BUILD_DATE_FID, build_date, "%lld\n");
+TDX_SYSFS_ATTR(TDX_SYS_FEATURES0_FID, features0, "%llx\n");
+
+static struct attribute *version_attrs[] = {
+	&minor_attr.attr,
+	&major_attr.attr,
+	&update_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group version_attr_group = {
+	.name = "version",
+	.attrs = version_attrs,
+};
+
+static struct attribute *properties_attrs[] = {
+	&build_num_attr.attr,
+	&build_date_attr.attr,
+	&features0_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group properties_attr_group = {
+	.name = "properties",
+	.attrs = properties_attrs,
+};

arch/x86/virt/vmx/tdx/tdx.c u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page) · line 1923

Quoted 10 lines

arch/x86/virt/vmx/tdx/tdx.c +10 -0

+
+__init static int tdh_sysfs_init(void)
+{
+	struct kobject *tdx_kobj;
+	int ret;
+
+	if (!hypervisor_kobj)
+		return -ENOMEM;
+
+	tdx_kobj = kobject_create_and_add("tdx", hypervisor_kobj);

So this "/sys/hypervisor" proposal is clearly unaware of some other discussions that have been happening around sysfs ABI for TEE Security Managers like the PSP or TDX Module [1]. That PCI/TSM series discusses the motivation for a bus/class + device model, not just raw hand-crafted kobjects.

My other concern for hand-crafted kobjects is that it also destroys the relationship with other existing objects. A /sys/hypervisor/$technology is awkward when ABI like Documentation/ABI/testing/sysfs-driver-ccp already exists.

So, no, I am not on board with this proposal. There are already patches in flight to have TDX create a 'struct device' object that plays a similar role as the PSP device object. For any potential common attributes across vendors the proposal is that be handled via a typical sysfs class device construction that links back to the $technology device. That "tsm" class device is present in the PCI/TSM series [1].

[1]: http://lore.kernel.org/174107245357.1288555.10863541957822891561.stgit@dwillia2-xfh.jf.intel.com

Quoted 15 lines · Dan Williams

Quoted 14 lines · Alexey Gladkov

From: "Alexey Gladkov (Intel)" <[email protected]>

Expose the TDX module information to userspace. The version information is valuable for debugging, as knowing the exact module version can help reproduce TDX-related issues.

Signed-off-by Alexey Gladkov (Intel) <[email protected]>

---
 arch/x86/Kconfig                  |  1 +
 arch/x86/include/asm/shared/tdx.h |  2 +
 arch/x86/include/asm/tdx.h        | 12 +++++
 arch/x86/virt/vmx/tdx/tdx.c       | 74 +++++++++++++++++++++++++++++++
 4 files changed, 89 insertions(+)

Quoted 28 lines

arch/x86/virt/vmx/tdx/tdx.c u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page) · line 1923

Quoted 9 lines

arch/x86/virt/vmx/tdx/tdx.c +9 -0

+__init static int tdh_sysfs_init(void)
+{
+	struct kobject *tdx_kobj;
+	int ret;
+
+	if (!hypervisor_kobj)
+		return -ENOMEM;
+
+	tdx_kobj = kobject_create_and_add("tdx", hypervisor_kobj);

So this "/sys/hypervisor" proposal is clearly unaware of some other discussions that have been happening around sysfs ABI for TEE Security Managers like the PSP or TDX Module [1]. That PCI/TSM series discusses the motivation for a bus/class + device model, not just raw hand-crafted kobjects.

My other concern for hand-crafted kobjects is that it also destroys the relationship with other existing objects. A /sys/hypervisor/$technology is awkward when ABI like Documentation/ABI/testing/sysfs-driver-ccp already exists.

So, no, I am not on board with this proposal. There are already patches in flight to have TDX create a 'struct device' object that plays a similar role as the PSP device object. For any potential common attributes across vendors the proposal is that be handled via a typical sysfs class device construction that links back to the $technology device. That "tsm" class device is present in the PCI/TSM series [1].

Quoted 1 line

[1]: http://lore.kernel.org/174107245357.1288555.10863541957822891561.stgit@dwillia2-xfh.jf.intel.com

Dan, could you elaborate on what is actual proposal? I am not sure I understand what 'struct device' can have info on TDX module version be attached to it.

Quoted 16 lines · Kirill A . Shutemov

Quoted 15 lines · Dan Williams

Quoted 14 lines · Alexey Gladkov

From: "Alexey Gladkov (Intel)" <[email protected]>

Expose the TDX module information to userspace. The version information is valuable for debugging, as knowing the exact module version can help reproduce TDX-related issues.

Signed-off-by Alexey Gladkov (Intel) <[email protected]>

---
 arch/x86/Kconfig                  |  1 +
 arch/x86/include/asm/shared/tdx.h |  2 +
 arch/x86/include/asm/tdx.h        | 12 +++++
 arch/x86/virt/vmx/tdx/tdx.c       | 74 +++++++++++++++++++++++++++++++
 4 files changed, 89 insertions(+)

[..]

Quoted 28 lines

Quoted 28 lines

arch/x86/virt/vmx/tdx/tdx.c u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page) · line 1923

Quoted 9 lines

arch/x86/virt/vmx/tdx/tdx.c +9 -0

+__init static int tdh_sysfs_init(void)
+{
+	struct kobject *tdx_kobj;
+	int ret;
+
+	if (!hypervisor_kobj)
+		return -ENOMEM;
+
+	tdx_kobj = kobject_create_and_add("tdx", hypervisor_kobj);

So this "/sys/hypervisor" proposal is clearly unaware of some other discussions that have been happening around sysfs ABI for TEE Security Managers like the PSP or TDX Module [1]. That PCI/TSM series discusses the motivation for a bus/class + device model, not just raw hand-crafted kobjects.

My other concern for hand-crafted kobjects is that it also destroys the relationship with other existing objects. A /sys/hypervisor/$technology is awkward when ABI like Documentation/ABI/testing/sysfs-driver-ccp already exists.

So, no, I am not on board with this proposal. There are already patches in flight to have TDX create a 'struct device' object that plays a similar role as the PSP device object. For any potential common attributes across vendors the proposal is that be handled via a typical sysfs class device construction that links back to the $technology device. That "tsm" class device is present in the PCI/TSM series [1].

Quoted 5 lines

Quoted 1 line

[1]: http://lore.kernel.org/174107245357.1288555.10863541957822891561.stgit@dwillia2-xfh.jf.intel.com

Dan, could you elaborate on what is actual proposal? I am not sure I understand what 'struct device' can have info on TDX module version be attached to it.

Confused, you do not understand that devices can have sysfs attributes?

Documentation/ABI/testing/sysfs-driver-ccp describes a device object and sysfs attributes for SEV-SNP firmware status.

For TDX, the proposal is to create virtual device to stand in for the lack of a PCI device that fills the same role as AMD PSP.

With the expectation that all TSM technolgies (SEV-SNP, TDX, CCA, etc) register a device, udev rules can trigger off a common class device uevent. That proposal is detailed here [1]:

[1]: http://lore.kernel.org/174107247268.1288555.9365605713564715054.stgit@dwillia2-xfh.jf.intel.com

Quoted 5 lines

Quoted 3 lines

Dan, could you elaborate on what is actual proposal? I am not sure I understand what 'struct device' can have info on TDX module version be attached to it.

Confused, you do not understand that devices can have sysfs attributes?

I didn't understand what device it would be in TDX case.

Quoted 5 lines

Documentation/ABI/testing/sysfs-driver-ccp describes a device object and sysfs attributes for SEV-SNP firmware status.

For TDX, the proposal is to create virtual device to stand in for the lack of a PCI device that fills the same role as AMD PSP.

Okay, I got it.

Do you see a problem having the same interface for both host and guest? We obviously need indication what level we are running on.

Quoted 5 lines

With the expectation that all TSM technolgies (SEV-SNP, TDX, CCA, etc) register a device, udev rules can trigger off a common class device uevent. That proposal is detailed here [1]:

[1]: http://lore.kernel.org/174107247268.1288555.9365605713564715054.stgit@dwillia2-xfh.jf.intel.com

Joerg, what do you think? How does it fit your ideas for SEV-SNP?