linux-kernel - Re: [PATCH 13/21] KVM: x86/mmu: Pass around full 64-bit error code for KVM page faults

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Message-ID: <CABgObfaGhH1aQyR-k_x=yrSRE3uwDpx9JJoMdiAdJCq72-O4DA@mail.gmail.com>
Date: Fri, 5 Apr 2024 19:57:53 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Xiaoyao Li <xiaoyao.li@...el.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, seanjc@...gle.com, 
	michael.roth@....com, isaku.yamahata@...el.com, thomas.lendacky@....com
Subject: Re: [PATCH 13/21] KVM: x86/mmu: Pass around full 64-bit error code
 for KVM page faults

On Mon, Mar 4, 2024 at 9:57 AM Xiaoyao Li <xiaoyao.li@...el.com> wrote:
>
> On 2/28/2024 7:20 AM, Paolo Bonzini wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> >
> ...
> > The use of lower_32_bits() moves from kvm_mmu_page_fault() to
> > FNAME(page_fault), since walking is independent of the data in the
> > upper bits of the error code.
>
> Is it a must? I don't see any issue if full u64 error_code is passed to
> FNAME(page_fault) as well.

The full error code *is* passed to kvm_mmu_do_page_fault() and
FNAME(page_fault), it's only dropped when passed to FNAME(walk_addr).

Paolo