[PATCH 69/70] x86/cpufeature: Add SEV_ES_GUEST CPU Feature

Joerg Roedel
2020-03-19T09:15:35Z

From: Joerg Roedel <jroedel@suse.de>

The feature bit will indicate whether the kernel runs as an SEV-ES
guest. This can be used to apply alternatives at boot for SEV-ES guests
and provides a way for user-space to detect whether it runs as an SEV-ES
guest.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kernel/cpu/amd.c | 6 +++++-
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 2fee1a2cac2f..35df826ee3fc 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -235,6 +235,7 @@
#define X86_FEATURE_VMCALL ( 8*32+18) /* "" Hypervisor supports the VMCALL instruction */
#define X86_FEATURE_VMW_VMMCALL ( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */
#define X86_FEATURE_SEV_ES ( 8*32+20) /* AMD Secure Encrypted Virtualization - Encrypted State */
+#define X86_FEATURE_SEV_ES_GUEST ( 8*32+21) /* SEV-ES Guest */

/* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
#define X86_FEATURE_FSGSBASE ( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 523a6a76c6c1..8cdb190822de 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -485,7 +485,6 @@ static void early_init_amd_mc(struct cpuinfo_x86 *c)

static void bsp_init_amd(struct cpuinfo_x86 *c)
{
-
#ifdef CONFIG_X86_64
if (c->x86 >= 0xf) {
unsigned long long tseg;
@@ -614,6 +613,11 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
setup_clear_cpu_cap(X86_FEATURE_SEV);
setup_clear_cpu_cap(X86_FEATURE_SEV_ES);
}
+
+ if (!rdmsrl_safe(MSR_AMD64_SEV, &msr)) {
+ if (msr & MSR_AMD64_SEV_ES_ENABLED)
+ set_cpu_cap(c, X86_FEATURE_SEV_ES_GUEST);
+ }
}

static void early_init_amd(struct cpuinfo_x86 *c)
--
2.17.1