Received-SPF: pass (google.com: domain of linux-kernel+bounces-87543-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Precedence: bulk
MIME-Version: 1.0
References: <20240228024147.41573-1-seanjc@google.com> <20240228024147.41573-3-seanjc@google.com>
 <CABgObfbtPJ6AAX9GnjNscPRTbNAOtamdxX677kx_r=zd4scw6w@mail.gmail.com> <ZeDPgx1O_AuR2Iz3@google.com>
In-Reply-To: <ZeDPgx1O_AuR2Iz3@google.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 29 Feb 2024 21:56:04 +0100
Message-ID: <CABgObfaXQR7WaUwjvBz-1yJN3fyysj1BMyY0S9L3DbizWjgrSQ@mail.gmail.com>
Subject: Re: [PATCH 02/16] KVM: x86: Remove separate "bit" defines for page
 fault error code masks
To: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, 
	Yan Zhao <yan.y.zhao@intel.com>, Isaku Yamahata <isaku.yamahata@intel.com>, 
	Michael Roth <michael.roth@amd.com>, Yu Zhang <yu.c.zhang@linux.intel.com>, 
	Chao Peng <chao.p.peng@linux.intel.com>, Fuad Tabba <tabba@google.com>, 
	David Matlack <dmatlack@google.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Thu, Feb 29, 2024 at 7:40=E2=80=AFPM Sean Christopherson <seanjc@google.=
com> wrote:
> Long story short, I think we should get to the below (I'll post a separat=
e series,
> assuming I'm not missing something).
>
>         unsigned long rflags =3D static_call(kvm_x86_get_rflags)(vcpu);
>         unsigned int pfec =3D access & (PFERR_PRESENT_MASK |
>                                       PFERR_WRITE_MASK |
>                                       PFERR_USER_MASK |
>                                       PFERR_FETCH_MASK);
>
>         /*
>          * For explicit supervisor accesses, SMAP is disabled if EFLAGS.A=
C =3D 1.
>          * For implicit supervisor accesses, SMAP cannot be overridden.
>          *
>          * SMAP works on supervisor accesses only, and not_smap can
>          * be set or not set when user access with neither has any bearin=
g
>          * on the result.
>          *
>          * We put the SMAP checking bit in place of the PFERR_RSVD_MASK b=
it;
>          * this bit will always be zero in pfec, but it will be one in in=
dex
>          * if SMAP checks are being disabled.
>          */
>         u64 implicit_access =3D access & PFERR_IMPLICIT_ACCESS;
>         bool not_smap =3D ((rflags & X86_EFLAGS_AC) | implicit_access) =
=3D=3D X86_EFLAGS_AC;
>         int index =3D (pfec | (not_smap ? PFERR_RSVD_MASK : 0)) >> 1;
>         u32 errcode =3D PFERR_PRESENT_MASK;
>         bool fault;

Sounds good.  The whole series is

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

apart from the small nits that were pointed out here and there.

Paolo