[GIT PULL] x86 fixes

Ingo Molnar
2023-10-01T09:04:53Z

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(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 382d4e6b848d..4e5ffc8b0e46 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -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),
{}
};
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 91fa70e51004..279148e72459 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -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)
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 3a43a2dee658..9c9faa1634fb 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -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.