The following commit has been merged into the x86/sev branch of tip:
Commit-ID: e221804dad4e6fe3a0cf192ba3c42cd2f328bdac
Gitweb: https://git.kernel.org/tip/e221804dad4e6fe3a0cf192ba3c42cd2f328bdac
Author: Alexey Kardashevskiy <aik@xxxxxxx>
AuthorDate: Wed, 16 Aug 2023 12:21:22 +10:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Wed, 16 Aug 2023 10:13:42 +02:00
x86/sev: Do not handle #VC for DR7 read/write
With MSR_AMD64_SEV_DEBUG_SWAP enabled, the guest is not expected to
receive a #VC for reads or writes of DR7.
Update the SNP_FEATURES_PRESENT mask with MSR_AMD64_SNP_DEBUG_SWAP so
an SNP guest doesn't gracefully terminate during SNP feature negotiation
if MSR_AMD64_SEV_DEBUG_SWAP is enabled.
Since a guest is not expected to receive a #VC on DR7 accesses when
MSR_AMD64_SEV_DEBUG_SWAP is enabled, return an error from the #VC
handler in this situation.
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Carlos Bilbao <carlos.bilbao@xxxxxxx>
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Reviewed-by: Pankaj Gupta <pankaj.gupta@xxxxxxx>
Link: https://lore.kernel.org/r/20230816022122.981998-1-aik@xxxxxxx
---
arch/x86/boot/compressed/sev.c | 2 +-
arch/x86/kernel/sev.c | 6 ++++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index c3e343b..e83e710 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -365,7 +365,7 @@ static void enforce_vmpl0(void)
* by the guest kernel. As and when a new feature is implemented in the
* guest kernel, a corresponding bit should be added to the mask.
*/
-#define SNP_FEATURES_PRESENT (0)
+#define SNP_FEATURES_PRESENT MSR_AMD64_SNP_DEBUG_SWAP
void snp_check_features(void)
{
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 1ee7bed..d380c93 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -1575,6 +1575,9 @@ static enum es_result vc_handle_dr7_write(struct ghcb *ghcb,
long val, *reg = vc_insn_get_rm(ctxt);
enum es_result ret;
+ if (sev_status & MSR_AMD64_SNP_DEBUG_SWAP)
+ return ES_VMM_ERROR;
+
if (!reg)
return ES_DECODE_FAILED;
@@ -1612,6 +1615,9 @@ static enum es_result vc_handle_dr7_read(struct ghcb *ghcb,
struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
long *reg = vc_insn_get_rm(ctxt);
+ if (sev_status & MSR_AMD64_SNP_DEBUG_SWAP)
+ return ES_VMM_ERROR;
+
if (!reg)
return ES_DECODE_FAILED;
|