linux-kernel - Re: [PATCH] KVM: x86/mmu: Precisely invalidate MMU root

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Message-ID: <171262750553.1420874.9114935191255728552.b4-ty@google.com>
Date: Mon,  8 Apr 2024 19:01:35 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzbot+dc308fcfcd53f987de73@...kaller.appspotmail.com, 
	Phi Nguyen <phind.uet@...il.com>
Subject: Re: [PATCH] KVM: x86/mmu: Precisely invalidate MMU root_role during
 CPUID update

On Mon, 08 Apr 2024 16:11:15 -0700, Sean Christopherson wrote:
> Set kvm_mmu_page_role.invalid to mark the various MMU root_roles invalid
> during CPUID update in order to force a refresh, instead of zeroing out
> the entire role.  This fixes a bug where kvm_mmu_free_roots() incorrectly
> thinks a root is indirect, i.e. not a TDP MMU, due to "direct" being
> zeroed, which in turn causes KVM to take mmu_lock for write instead of
> read.
> 
> [...]

Applied super quickly to kvm-x86 fixes, so that it gets time in -next before I
pass it on to Paolo.  This is the last commit in "fixes", so it's easy to drop
and/or modify if there's an issue.

[1/1] KVM: x86/mmu: Precisely invalidate MMU root_role during CPUID update
      https://github.com/kvm-x86/linux/commit/4fa96da3e6fe

--
https://github.com/kvm-x86/linux/tree/next