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x86 fixes

GIT PULL Merged Ingo Molnar 2 participants 2 messages Oct 1, 2023

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x86 Intel SGX
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Ingo Molnar

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Linus,

Please pull the latest x86/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2023-10-01

# HEAD: c6c2adcba50c2622ed25ba5d5e7f05f584711358 x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race

Misc fixes: a kerneldoc build warning fix, add SRSO mitigation for AMD-derived Hygon processors, and fix a SGX kernel crash in the page fault handler that can trigger when ksgxd races to reclaim the SECS special page, by making the SECS page unswappable.

Thanks,

Ingo

------------------>
Christophe JAILLET (1):
x86/kgdb: Fix a kerneldoc warning when build with W=1

Haitao Huang (1):
x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race

Pu Wen (1):
x86/srso: Add SRSO mitigation for Hygon processors

 arch/x86/kernel/cpu/common.c   |  2 +-
 arch/x86/kernel/cpu/sgx/encl.c | 30 +++++++++++++++++++++++++-----
 arch/x86/kernel/kgdb.c         |  1 -
 3 files changed, 26 insertions(+), 7 deletions(-)
arch/x86/kernel/cpu/common.c +1 -1
index 382d4e6b848d..4e5ffc8b0e46 100644
@@ -1303,7 +1303,7 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
 	VULNBL_AMD(0x15, RETBLEED),
 	VULNBL_AMD(0x16, RETBLEED),
 	VULNBL_AMD(0x17, RETBLEED | SMT_RSB | SRSO),
-	VULNBL_HYGON(0x18, RETBLEED | SMT_RSB),
+	VULNBL_HYGON(0x18, RETBLEED | SMT_RSB | SRSO),
 	VULNBL_AMD(0x19, SRSO),
 	{}
 };
arch/x86/kernel/cpu/sgx/encl.c +25 -5
index 91fa70e51004..279148e72459 100644
@@ -235,6 +235,21 @@ static struct sgx_epc_page *sgx_encl_eldu(struct sgx_encl_page *encl_page,
 	return epc_page;
 }
 
+/*
+ * Ensure the SECS page is not swapped out.  Must be called with encl->lock
+ * to protect the enclave states including SECS and ensure the SECS page is
+ * not swapped out again while being used.
+ */
+static struct sgx_epc_page *sgx_encl_load_secs(struct sgx_encl *encl)
+{
+	struct sgx_epc_page *epc_page = encl->secs.epc_page;
+
+	if (!epc_page)
+		epc_page = sgx_encl_eldu(&encl->secs, NULL);
+
+	return epc_page;
+}
+
 static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
 						  struct sgx_encl_page *entry)
 {

@@ -248,11 +263,9 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
 		return entry;
 	}
 
-	if (!(encl->secs.epc_page)) {
-		epc_page = sgx_encl_eldu(&encl->secs, NULL);
-		if (IS_ERR(epc_page))
-			return ERR_CAST(epc_page);
-	}
+	epc_page = sgx_encl_load_secs(encl);
+	if (IS_ERR(epc_page))
+		return ERR_CAST(epc_page);
 
 	epc_page = sgx_encl_eldu(entry, encl->secs.epc_page);
 	if (IS_ERR(epc_page))

@@ -339,6 +352,13 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 
 	mutex_lock(&encl->lock);
 
+	epc_page = sgx_encl_load_secs(encl);
+	if (IS_ERR(epc_page)) {
+		if (PTR_ERR(epc_page) == -EBUSY)
+			vmret = VM_FAULT_NOPAGE;
+		goto err_out_unlock;
+	}
+
 	epc_page = sgx_alloc_epc_page(encl_page, false);
 	if (IS_ERR(epc_page)) {
 		if (PTR_ERR(epc_page) == -EBUSY)
arch/x86/kernel/kgdb.c +0 -1
index 3a43a2dee658..9c9faa1634fb 100644
@@ -695,7 +695,6 @@ void kgdb_arch_exit(void)
 }
 
 /**
- *
  *	kgdb_skipexception - Bail out of KGDB when we've been triggered.
  *	@exception: Exception vector number
  *	@regs: Current &struct pt_regs.