On Thu, Sep 1, 2022 at 5:45 AM Shukla, Santosh <santosh.shukla@xxxxxxx> wrote: > > Hi Jim, > > On 9/1/2022 5:12 AM, Jim Mattson wrote: > > On Mon, Aug 29, 2022 at 3:09 AM Santosh Shukla <santosh.shukla@xxxxxxx> wrote: > >> > >> VNMI feature allows the hypervisor to inject NMI into the guest w/o > >> using Event injection mechanism, The benefit of using VNMI over the > >> event Injection that does not require tracking the Guest's NMI state and > >> intercepting the IRET for the NMI completion. VNMI achieves that by > >> exposing 3 capability bits in VMCB intr_cntrl which helps with > >> virtualizing NMI injection and NMI_Masking. > >> > >> The presence of this feature is indicated via the CPUID function > >> 0x8000000A_EDX[25]. > >> > >> Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> > >> Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx> > >> --- > >> arch/x86/include/asm/cpufeatures.h | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h > >> index ef4775c6db01..33e3603be09e 100644 > >> --- a/arch/x86/include/asm/cpufeatures.h > >> +++ b/arch/x86/include/asm/cpufeatures.h > >> @@ -356,6 +356,7 @@ > >> #define X86_FEATURE_VGIF (15*32+16) /* Virtual GIF */ > >> #define X86_FEATURE_X2AVIC (15*32+18) /* Virtual x2apic */ > >> #define X86_FEATURE_V_SPEC_CTRL (15*32+20) /* Virtual SPEC_CTRL */ > >> +#define X86_FEATURE_V_NMI (15*32+25) /* Virtual NMI */ > >> #define X86_FEATURE_SVME_ADDR_CHK (15*32+28) /* "" SVME addr check */ > > > > Why is it "V_NMI," but "VGIF"? > > > I guess you are asking why I chose V_NMI and not VNMI, right? > if so then there are two reasons for going with V_NMI - IP bits are named in order > V_NMI, V_NMI_MASK, and V_NMI_ENABLE style and also Intel already using VNMI (X86_FEATURE_VNMI) I would argue that inconsistency and arbitrary underscores unnecessarily increase the cognitive load. It is not immediately obvious to me that an extra underscore implies AMD. What's wrong with X86_FEATURE_AMD_VNMI? We already have over half a dozen AMD feature bits that are distinguished from the Intel version by an AMD prefix.
