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SubjectRe: [PATCH 1/6] KVM: x86: Inject #GP if WRMSR sets reserved bits in APIC Self-IPI
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On Sat, 2023-01-07 at 01:10 +0000, Sean Christopherson wrote:
> Inject a #GP if the guest attempts to set reserved bits in the x2APIC-only
> Self-IPI register. Bits 7:0 hold the vector, all other bits are reserved.
>
> Reported-by: Marc Orr <marcorr@google.com>
> Cc: Ben Gardon <bgardon@google.com>
> Cc: Venkatesh Srinivas <venkateshs@chromium.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/lapic.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 80f92cbc4029..f77da92c6ea6 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2315,10 +2315,14 @@ static int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
> break;
>
> case APIC_SELF_IPI:
> - if (apic_x2apic_mode(apic))
> - kvm_apic_send_ipi(apic, APIC_DEST_SELF | (val & APIC_VECTOR_MASK), 0);
> - else
> + /*
> + * Self-IPI exists only when x2APIC is enabled. Bits 7:0 hold
> + * the vector, everything else is reserved.
> + */
> + if (!apic_x2apic_mode(apic) || (val & ~APIC_VECTOR_MASK))
> ret = 1;
> + else
> + kvm_apic_send_ipi(apic, APIC_DEST_SELF | val, 0);
> break;
> default:
> ret = 1;

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
Maxim Levitsky

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