From: Paolo Bonzini <pbonzini@redhat.com>
To: Marc Orr <marcorr@google.com>, Tom Lendacky <Thomas.Lendacky@amd.com>
Cc: seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com,
jmattson@google.com, joro@8bytes.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, hpa@zytor.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Always set kvm_run->if_flag
Date: Thu, 9 Dec 2021 18:52:01 +0100 [thread overview]
Message-ID: <0d540a6b-8838-bdf5-ddad-f3b9576ca9f2@redhat.com> (raw)
In-Reply-To: <CAA03e5Gf=ZsAKhuLCEtYCCf0UuNXSHRXQHgmjOj3MKtbiSMbqQ@mail.gmail.com>
On 12/7/21 18:28, Marc Orr wrote:
>>>>> +static bool svm_get_if_flag(struct kvm_vcpu *vcpu)
>>>>> +{
>>>>> + struct vmcb *vmcb = to_svm(vcpu)->vmcb;
>>>>> +
>>>>> + return !!(vmcb->control.int_state & SVM_GUEST_INTERRUPT_MASK);
>>>> I'm not sure if this is always valid to use for non SEV-ES guests. Maybe
>>>> the better thing would be:
>>>>
>>>> return sev_es_guest(vcpu->kvm) ? vmcb->control.int_state & SVM_GUEST_INTERRUPT_MASK
>>>> : kvm_get_rflags(vcpu) & X86_EFLAGS_IF;
>>>>
>>>> (Since this function returns a bool, I don't think you need the !!)
>>>
>>> I had the same reservations when writing the patch. (Why fix what's
>>> not broken.) The reason I wrote the patch this way is based on what I
>>> read in APM vol2: Appendix B Layout of VMCB: "GUEST_INTERRUPT_MASK -
>>> Value of the RFLAGS.IF bit for the guest."
>>
>> I just verified with the hardware team that this flag is indeed only set
>> for a guest with protected state (SEV-ES / SEV-SNP). An update to the APM
>> will be made.
>
> Got it now. Then the change you suggested is a must! Thanks, Tom.
Besides, the bit wouldn't have existed on old (pre-SEV-ES) processors.
Paolo
prev parent reply other threads:[~2021-12-09 17:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 4:31 [PATCH] KVM: x86: Always set kvm_run->if_flag Marc Orr
2021-12-07 4:49 ` Jim Mattson
2021-12-07 14:43 ` Tom Lendacky
2021-12-07 15:14 ` Marc Orr
2021-12-07 15:33 ` Maxim Levitsky
2021-12-07 16:00 ` Tom Lendacky
2021-12-07 16:34 ` Sean Christopherson
2021-12-07 17:28 ` Marc Orr
2021-12-07 17:28 ` Marc Orr
2021-12-09 17:52 ` Paolo Bonzini [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=0d540a6b-8838-bdf5-ddad-f3b9576ca9f2@redhat.com \
--to=pbonzini@redhat.com \
--cc=Thomas.Lendacky@amd.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marcorr@google.com \
--cc=mingo@redhat.com \
--cc=seanjc@google.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox