From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "pbonzini@redhat.com" <pbonzini@redhat.com>,
"seanjc@google.com" <seanjc@google.com>
Cc: "sashiko-bot@kernel.org" <sashiko-bot@kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Huang, Kai" <kai.huang@intel.com>,
"Zhao, Yan Y" <yan.y.zhao@intel.com>
Subject: Re: [PATCH 2/4] KVM: x86/mmu: Harden "map private PFN" against unexpected root invalidation
Date: Fri, 7 Aug 2026 20:26:35 +0000 [thread overview]
Message-ID: <a05089fa3c5aa0ec9cdbd88d8aefc7b9ffa77e0d.camel@intel.com> (raw)
In-Reply-To: <20260806214050.78058-3-seanjc@google.com>
On Thu, 2026-08-06 at 14:40 -0700, Sean Christopherson wrote:
> @@ -5199,10 +5195,21 @@ int kvm_tdp_mmu_map_private_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn)
> if (kvm_test_request(KVM_REQ_VM_DEAD, vcpu))
> return -EIO;
>
> + r = kvm_mmu_reload(vcpu);
> + if (r)
> + return r;
> +
> cond_resched();
>
> guard(read_lock)(&kvm->mmu_lock);
>
> + /*
> + * Because slots_lock is held, it should be impossible for roots
> + * to be invalidated after the initial MMU reload. WARN, but
> + * continue and re-reload the MMU to try and keep the VM alive.
> + */
It might be a little confusing when no MMU reload follows the comment. Maybe
mention that the MMU reload is above? Either way ok to me.
> + WARN_ON_ONCE(kvm_test_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu));
> +
> r = kvm_tdp_mmu_map(vcpu, &fault);
next prev parent reply other threads:[~2026-08-07 20:26 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 21:40 [PATCH 0/4] KVM: x86/mmu: Fix pre-fault and map private loops Sean Christopherson
2026-08-06 21:40 ` [PATCH 1/4] KVM: x86/mmu: Reload MMU on *every* page pre-fault attempt/iteration Sean Christopherson
2026-08-07 8:58 ` Huang, Kai
2026-08-07 19:04 ` Edgecombe, Rick P
2026-08-07 19:11 ` Sean Christopherson
2026-08-06 21:40 ` [PATCH 2/4] KVM: x86/mmu: Harden "map private PFN" against unexpected root invalidation Sean Christopherson
2026-08-07 20:26 ` Edgecombe, Rick P [this message]
2026-08-07 22:18 ` Sean Christopherson
2026-08-06 21:40 ` [PATCH 3/4] KVM: x86/mmu: Top-up memory caches when retrying "map private PFN" Sean Christopherson
2026-08-07 20:38 ` Edgecombe, Rick P
2026-08-07 22:13 ` Sean Christopherson
2026-08-06 21:40 ` [PATCH 4/4] KVM: x86/mmu: Add sanity check to detect stale page faults in " Sean Christopherson
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