linux-kernel - Re: [PATCH v6 39/44] KVM: VMX: Bug the VM if either MSR auto-load list is full

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Message-ID: <aWANuxukqWmo36N0@google.com>
Date: Thu, 8 Jan 2026 12:04:11 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oupton@...nel.org>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Xin Li <xin@...or.com>, "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Paolo Bonzini <pbonzini@...hat.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, kvm@...r.kernel.org, loongarch@...ts.linux.dev, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, 
	Mingwei Zhang <mizhang@...gle.com>, Xudong Hao <xudong.hao@...el.com>, 
	Sandipan Das <sandipan.das@....com>, Xiong Zhang <xiong.y.zhang@...ux.intel.com>, 
	Manali Shukla <manali.shukla@....com>, Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v6 39/44] KVM: VMX: Bug the VM if either MSR auto-load
 list is full

On Mon, Dec 08, 2025, Dapeng Mi wrote:
> On 12/6/2025 8:17 AM, Sean Christopherson wrote:
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index 38491962b2c1..2c50ebf4ff1b 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -1098,6 +1098,7 @@ static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
> >  {
> >  	int i, j = 0;
> >  	struct msr_autoload *m = &vmx->msr_autoload;
> > +	struct kvm *kvm = vmx->vcpu.kvm;
> >  
> >  	switch (msr) {
> >  	case MSR_EFER:
> > @@ -1134,12 +1135,10 @@ static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
> >  	i = vmx_find_loadstore_msr_slot(&m->guest, msr);
> >  	j = vmx_find_loadstore_msr_slot(&m->host, msr);
> >  
> > -	if ((i < 0 && m->guest.nr == MAX_NR_LOADSTORE_MSRS) ||
> > -	    (j < 0 &&  m->host.nr == MAX_NR_LOADSTORE_MSRS)) {
> > -		printk_once(KERN_WARNING "Not enough msr switch entries. "
> > -				"Can't add msr %x\n", msr);
> > +	if (KVM_BUG_ON(i < 0 && m->guest.nr == MAX_NR_LOADSTORE_MSRS, kvm) ||
> > +	    KVM_BUG_ON(j < 0 &&  m->host.nr == MAX_NR_LOADSTORE_MSRS, kvm))
> 
> nit: Remove one extra space before "m->host.nr".

Oh, that's intentional, so that the rest of the line is aligned with the "guest"
line above.