linux-kernel - Re: [PATCH] KVM: x86/pmu: Disable support for adaptive PEBS

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Message-ID: <171262710736.1419672.15334456430797702599.b4-ty@google.com>
Date: Mon,  8 Apr 2024 19:01:37 -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, 
	Like Xu <like.xu.linux@...il.com>, Mingwei Zhang <mizhang@...gle.com>, 
	Zhenyu Wang <zhenyuw@...ux.intel.com>, Zhang Xiong <xiong.y.zhang@...el.com>, 
	Lv Zhiyuan <zhiyuan.lv@...el.com>, Dapeng Mi <dapeng1.mi@...el.com>, 
	Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH] KVM: x86/pmu: Disable support for adaptive PEBS

On Wed, 06 Mar 2024 16:58:33 -0800, Sean Christopherson wrote:
> Drop support for virtualizing adaptive PEBS, as KVM's implementation is
> architecturally broken without an obvious/easy path forward, and because
> exposing adaptive PEBS can leak host LBRs to the guest, i.e. can leak
> host kernel addresses to the guest.
> 
> Bug #1 is that KVM doesn't doesn't account for the upper 32 bits of
> IA32_FIXED_CTR_CTRL when (re)programming fixed counters, e.g
> fixed_ctrl_field() drops the upper bits, reprogram_fixed_counters()
> stores local variables as u8s and truncates the upper bits too, etc.
> 
> [...]

Applied to kvm-x86 fixes, thanks!

[1/1] KVM: x86/pmu: Disable support for adaptive PEBS
      https://github.com/kvm-x86/linux/commit/9e985cbf2942

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