On Thu, 2022-06-02 at 19:56 +0530, Santosh Shukla wrote:
> VNMI exposes 3 capability bits (V_NMI, V_NMI_MASK, and V_NMI_ENABLE) to
> virtualize NMI and NMI_MASK, Those capability bits are part of
> VMCB::intr_ctrl -
> V_NMI(11) - Indicates whether a virtual NMI is pending in the guest.
So this is like bit in IRR
> V_NMI_MASK(12) - Indicates whether virtual NMI is masked in the guest.
And that is like bit in ISR.
Question: what are the interactions with GIF/vGIF and this feature?
> V_NMI_ENABLE(26) - Enables the NMI virtualization feature for the guest.
>
> When Hypervisor wants to inject NMI, it will set V_NMI bit, Processor
> will clear the V_NMI bit and Set the V_NMI_MASK which means the Guest is
> handling NMI, After the guest handled the NMI, The processor will clear
> the V_NMI_MASK on the successful completion of IRET instruction Or if
> VMEXIT occurs while delivering the virtual NMI.
>
> To enable the VNMI capability, Hypervisor need to program
> V_NMI_ENABLE bit 1.
>
> Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx>
> ---
> arch/x86/include/asm/svm.h | 7 +++++++
> arch/x86/kvm/svm/svm.c | 6 ++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 1b07fba11704..22d918555df0 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -195,6 +195,13 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
> #define AVIC_ENABLE_SHIFT 31
> #define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)
>
> +#define V_NMI_PENDING_SHIFT 11
> +#define V_NMI_PENDING (1 << V_NMI_PENDING_SHIFT)
> +#define V_NMI_MASK_SHIFT 12
> +#define V_NMI_MASK (1 << V_NMI_MASK_SHIFT)
> +#define V_NMI_ENABLE_SHIFT 26
> +#define V_NMI_ENABLE (1 << V_NMI_ENABLE_SHIFT)
> +
> #define LBR_CTL_ENABLE_MASK BIT_ULL(0)
> #define VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK BIT_ULL(1)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 200045f71df0..860f28c668bd 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -198,6 +198,8 @@ module_param(dump_invalid_vmcb, bool, 0644);
> bool intercept_smi = true;
> module_param(intercept_smi, bool, 0444);
>
> +static bool vnmi;
> +module_param(vnmi, bool, 0444);
>
> static bool svm_gp_erratum_intercept = true;
>
> @@ -4930,6 +4932,10 @@ static __init int svm_hardware_setup(void)
> svm_x86_ops.vcpu_get_apicv_inhibit_reasons = NULL;
> }
>
> + vnmi = vnmi && boot_cpu_has(X86_FEATURE_V_NMI);
> + if (vnmi)
> + pr_info("V_NMI enabled\n");
> +
> if (vls) {
> if (!npt_enabled ||
> !boot_cpu_has(X86_FEATURE_V_VMSAVE_VMLOAD) ||
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Best regards,
Maxim Levitsky
