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Message-ID: <20240701084558.1620584f@jacob-builder>
Date: Mon, 1 Jul 2024 08:45:58 -0700
From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
To: Xin Li <xin@...or.com>
Cc: X86 Kernel <x86@...nel.org>, Sean Christopherson <seanjc@...gle.com>,
LKML <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
Dave Hansen <dave.hansen@...el.com>, "H. Peter Anvin" <hpa@...or.com>, Ingo
Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Xin Li
<xin3.li@...el.com>, linux-perf-users@...r.kernel.org, Peter Zijlstra
<peterz@...radead.org>, Paolo Bonzini <pbonzini@...hat.com>, Tony Luck
<tony.luck@...el.com>, Andy Lutomirski <luto@...nel.org>, acme@...nel.org,
kan.liang@...ux.intel.com, Andi Kleen <andi.kleen@...el.com>, "Mehta,
Sohil" <sohil.mehta@...el.com>, Zeng Guang <guang.zeng@...el.com>,
jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v3 07/11] KVM: VMX: Handle NMI Source report in VM exit
On Fri, 28 Jun 2024 21:07:04 -0700, Xin Li <xin@...or.com> wrote:
> On 6/28/2024 1:18 PM, Jacob Pan wrote:
> > From: Zeng Guang <guang.zeng@...el.com>
> >
> > If the "NMI exiting" VM-execution control is 1, the value of the 16-bit
> > NMI source vector is saved in the exit-qualification field in the VMCS
> > when VM exits occur on CPUs that support NMI source.
> >
> > KVM that is aware of NMI-source reporting will push the bitmask of NMI
> > source vectors as the exceptoin event data field on the stack for then
> > entry of FRED exception. Subsequently, the host NMI exception handler
> > is invoked which will process NMI source information in the event data.
> > This operation is independent of vCPU FRED enabling status.
> >
> > Signed-off-by: Zeng Guang <guang.zeng@...el.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > ---
> > arch/x86/entry/entry_64_fred.S | 2 +-
> > arch/x86/kvm/vmx/vmx.c | 11 ++++++++---
> > 2 files changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/x86/entry/entry_64_fred.S
> > b/arch/x86/entry/entry_64_fred.S index a02bc6f3d2e6..0d934a3fcaf8 100644
> > --- a/arch/x86/entry/entry_64_fred.S
> > +++ b/arch/x86/entry/entry_64_fred.S
> > @@ -92,7 +92,7 @@ SYM_FUNC_START(asm_fred_entry_from_kvm)
> > * +--------+-----------------+
> > */
> > push $0 /* Reserved, must be 0
> > */
> > - push $0 /* Event data, 0 for
> > IRQ/NMI */
> > + push %rsi /* Event data for IRQ/NMI */
> > push %rdi /* fred_ss handed in by the
> > caller */ push %rbp
> > pushf
>
> This belongs to the previous patch, it is part of the host changes.
right, will do.
>
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index 4e7b36081b76..6719c598fa5f 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -7331,10 +7331,15 @@ static noinstr void vmx_vcpu_enter_exit(struct
> > kvm_vcpu *vcpu, if ((u16)vmx->exit_reason.basic ==
> > EXIT_REASON_EXCEPTION_NMI && is_nmi(vmx_get_intr_info(vcpu))) {
> > kvm_before_interrupt(vcpu, KVM_HANDLING_NMI);
> > - if (cpu_feature_enabled(X86_FEATURE_FRED))
> > - fred_entry_from_kvm(EVENT_TYPE_NMI,
> > NMI_VECTOR, 0);
> > - else
> > + if (cpu_feature_enabled(X86_FEATURE_FRED)) {
> > + unsigned long edata = 0;
> > +
> > + if
> > (cpu_feature_enabled(X86_FEATURE_NMI_SOURCE))
> > + edata = vmx_get_exit_qual(vcpu);
> > + fred_entry_from_kvm(EVENT_TYPE_NMI,
> > NMI_VECTOR, edata);
>
> Simply do fred_entry_from_kvm(EVENT_TYPE_NMI, NMI_VECTOR,
> vmx_get_exit_qual(vcpu))?
I don't have strong preference but having a local variable improves
readability IMHO.
> > + } else {
> > vmx_do_nmi_irqoff();
> > + }
> > kvm_after_interrupt(vcpu);
> > }
> >
>
Thanks,
Jacob
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