| Message ID | 20250418095434.8281-1-heinrich.schuchardt@canonical.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [1/1] lib/fwts_cpu: correct determination of SEV enablement | expand |
Thanks for the patch. We're currently discussing the MSR behaviour with AMD engineers, but haven't received any feedback yet: https://lists.ubuntu.com/archives/fwts-devel/2025-April/013980.html Let's go ahead and apply this patch, test with MSR_VM_CR, and observe any potential impact going forward. Cheers, Ivan On 2025/4/18 17:54, Heinrich Schuchardt wrote: > MSR_FEATURE_CONTROL (0xC0000080) bit 12 changes > when module kvm_amd is loaded and unloaded. > > MSR_VM_CR (0xC0010114) bit 4 reflects the BIOS setting. > The SVMDIS—Bit is described in [1]. > > [1] > AMD64 Architecture Programmer’s Manual > Volume 2, System Programming > https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24593.pdf > 3.1.7 Extended Feature Enable Register (EFER), page 55 > > Link: https://bugs.launchpad.net/ubuntu/+source/fwts/+bug/2098458 > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> > --- > src/cpu/virt/virt_svm.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/src/cpu/virt/virt_svm.c b/src/cpu/virt/virt_svm.c > index d86f54f4..450a7f2a 100644 > --- a/src/cpu/virt/virt_svm.c > +++ b/src/cpu/virt/virt_svm.c > @@ -37,7 +37,7 @@ > #include <limits.h> > #include <errno.h> > > -#define MSR_FEATURE_CONTROL 0xC0000080 > +#define MSR_VM_CR 0xC0010114 > > extern fwts_cpuinfo_x86 *fwts_virt_cpuinfo; > > @@ -58,10 +58,10 @@ static int vt_locked_by_bios(fwts_framework *fw) > if (!can_lock_with_msr()) > return 0; > > - if (fwts_cpu_readmsr(fw, 0, MSR_FEATURE_CONTROL, &msr)) > + if (fwts_cpu_readmsr(fw, 0, MSR_VM_CR, &msr)) > return -1; > > - return ((msr & 0x1000) == 0x1000); /* SVM capable but locked by bios*/ > + return ((msr & 0x10) == 0x10); /* SVM locked */ > } > > void virt_check_svm(fwts_framework *fw)
diff --git a/src/cpu/virt/virt_svm.c b/src/cpu/virt/virt_svm.c index d86f54f4..450a7f2a 100644 --- a/src/cpu/virt/virt_svm.c +++ b/src/cpu/virt/virt_svm.c @@ -37,7 +37,7 @@ #include <limits.h> #include <errno.h> -#define MSR_FEATURE_CONTROL 0xC0000080 +#define MSR_VM_CR 0xC0010114 extern fwts_cpuinfo_x86 *fwts_virt_cpuinfo; @@ -58,10 +58,10 @@ static int vt_locked_by_bios(fwts_framework *fw) if (!can_lock_with_msr()) return 0; - if (fwts_cpu_readmsr(fw, 0, MSR_FEATURE_CONTROL, &msr)) + if (fwts_cpu_readmsr(fw, 0, MSR_VM_CR, &msr)) return -1; - return ((msr & 0x1000) == 0x1000); /* SVM capable but locked by bios*/ + return ((msr & 0x10) == 0x10); /* SVM locked */ } void virt_check_svm(fwts_framework *fw)
MSR_FEATURE_CONTROL (0xC0000080) bit 12 changes when module kvm_amd is loaded and unloaded. MSR_VM_CR (0xC0010114) bit 4 reflects the BIOS setting. The SVMDIS—Bit is described in [1]. [1] AMD64 Architecture Programmer’s Manual Volume 2, System Programming https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24593.pdf 3.1.7 Extended Feature Enable Register (EFER), page 55 Link: https://bugs.launchpad.net/ubuntu/+source/fwts/+bug/2098458 Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com> --- src/cpu/virt/virt_svm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)