The following commit has been merged into the x86/sev branch of tip:
Commit-ID: 4972808d6f4a2b4c10eb3035d769f2e1a003da2f
Gitweb: https://git.kernel.org/tip/4972808d6f4a2b4c10eb3035d769f2e1a003da2f
Author: Tom Lendacky <thomas.lendacky@xxxxxxx>
AuthorDate: Mon, 02 Dec 2024 14:50:48 -06:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Sat, 14 Dec 2024 10:55:28 +01:00
x86/sev: Require the RMPREAD instruction after Zen4
Limit usage of the non-architectural RMP format to Zen3/Zen4 processors.
The RMPREAD instruction, with architectural defined output, is available
and should be used for RMP access beyond Zen4.
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Nikunj A Dadhania <nikunj@xxxxxxx>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@xxxxxxx>
Reviewed-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Link: https://lore.kernel.org/r/5be0093e091778a151266ea853352f62f838eb99.1733172653.git.thomas.lendacky@xxxxxxx
---
arch/x86/kernel/cpu/amd.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 79d2e17..b9592c6 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -355,10 +355,15 @@ static void bsp_determine_snp(struct cpuinfo_x86 *c)
/*
* RMP table entry format is not architectural and is defined by the
* per-processor PPR. Restrict SNP support on the known CPU models
- * for which the RMP table entry format is currently defined for.
+ * for which the RMP table entry format is currently defined or for
+ * processors which support the architecturally defined RMPREAD
+ * instruction.
*/
if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
- c->x86 >= 0x19 && snp_probe_rmptable_info()) {
+ (cpu_feature_enabled(X86_FEATURE_ZEN3) ||
+ cpu_feature_enabled(X86_FEATURE_ZEN4) ||
+ cpu_feature_enabled(X86_FEATURE_RMPREAD)) &&
+ snp_probe_rmptable_info()) {
cc_platform_set(CC_ATTR_HOST_SEV_SNP);
} else {
setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
|