linux-kernel - Re: [PATCH 03/28] KVM: SVM: Use ARRAY_SIZE() to iterate over direct_access

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Message-ID: <aD6q42o/o/fh9SrT@intel.com>
Date: Tue, 3 Jun 2025 15:57:23 +0800
From: Chao Gao <chao.gao@...el.com>
To: Sean Christopherson <seanjc@...gle.com>
CC: Paolo Bonzini <pbonzini@...hat.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...en8.de>, Xin Li
	<xin@...or.com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: Re: [PATCH 03/28] KVM: SVM: Use ARRAY_SIZE() to iterate over
 direct_access_msrs

On Thu, May 29, 2025 at 04:39:48PM -0700, Sean Christopherson wrote:
>Drop the unnecessary and dangerous value-terminated behavior of
>direct_access_msrs, and simply iterate over the actual size of the array.
>The use in svm_set_x2apic_msr_interception() is especially sketchy, as it
>relies on unused capacity being zero-initialized, and '0' being outside
>the range of x2APIC MSRs.
>
>To ensure the array and shadow_msr_intercept stay synchronized, simply
>assert that their sizes are identical (note the six 64-bit-only MSRs).
>
>Note, direct_access_msrs will soon be removed entirely; keeping the assert
>synchronized with the array isn't expected to be along-term maintenance
>burden.
>
>Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Chao Gao <chao.gao@...el.com>