linux-kernel - Re: [RFC PATCH 16/24] KVM: x86/mmu: Allow skipping the gva flush in kvm_mmu_invalidate

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Message-ID: <032981892a2ed9ff596ded9b5945342894fdb9ba.camel@redhat.com>
Date: Thu, 03 Apr 2025 16:10:23 -0400
From: Maxim Levitsky <mlevitsk@...hat.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>, Sean Christopherson
 <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jim Mattson <jmattson@...gle.com>, 
 Vitaly Kuznetsov <vkuznets@...hat.com>, Rik van Riel <riel@...riel.com>,
 Tom Lendacky <thomas.lendacky@....com>,  x86@...nel.org,
 kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 16/24] KVM: x86/mmu: Allow skipping the gva flush in
 kvm_mmu_invalidate_addr()

On Wed, 2025-03-26 at 19:36 +0000, Yosry Ahmed wrote:
> Refactor a helper out of kvm_mmu_invalidate_addr() that allows skipping
> the gva flush. This will be used when an invalidation is needed but the
> GVA TLB translations that require invalidation are not of the current
> context (e.g. when emulating INVLPGA for L1 to flush L2's translations).
> 
> No functional change intended.
> 
> Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
> ---
>  arch/x86/kvm/mmu/mmu.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4a72ada0a7585..e2b1994f12753 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -6355,15 +6355,15 @@ static void kvm_mmu_invalidate_addr_in_root(struct kvm_vcpu *vcpu,
>  	write_unlock(&vcpu->kvm->mmu_lock);
>  }
>  
> -void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> -			     u64 addr, unsigned long roots)
> +static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> +				      u64 addr, unsigned long roots, bool gva_flush)
>  {
>  	int i;
>  
>  	WARN_ON_ONCE(roots & ~KVM_MMU_ROOTS_ALL);
>  
>  	/* It's actually a GPA for vcpu->arch.guest_mmu.  */
> -	if (mmu != &vcpu->arch.guest_mmu) {
> +	if (gva_flush && mmu != &vcpu->arch.guest_mmu) {
>  		/* INVLPG on a non-canonical address is a NOP according to the SDM.  */
>  		if (is_noncanonical_invlpg_address(addr, vcpu))
>  			return;
> @@ -6382,6 +6382,12 @@ void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
>  			kvm_mmu_invalidate_addr_in_root(vcpu, mmu, addr, mmu->prev_roots[i].hpa);
>  	}
>  }
> +
> +void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> +			     u64 addr, unsigned long roots)
> +{
> +	__kvm_mmu_invalidate_addr(vcpu, mmu, addr, roots, true);
> +}
>  EXPORT_SYMBOL_GPL(kvm_mmu_invalidate_addr);
>  
>  void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)

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

Best regards,
	Maxim Levitsky