From: Paolo Bonzini <pbonzini@redhat.com>
To: Quan Xu <quan.xu0@gmail.com>, Rik van Riel <riel@redhat.com>,
"quan.xu04@gmail.com" <quan.xu04@gmail.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
david@redhat.com, borntraeger@de.ibm.com, tglx@linutronix.de,
rkrcmar@redhat.com
Subject: Re: [PATCH 1/2] x86,kvm: move qemu/guest FPU switching out to vcpu_run
Date: Thu, 16 Nov 2017 18:50:41 +0100 [thread overview]
Message-ID: <8396b51f-674d-74f9-e67f-026504c24631@redhat.com> (raw)
In-Reply-To: <d67cef62-3165-50cd-36e8-be7c555dc79e@gmail.com>
On 16/11/2017 15:28, Quan Xu wrote:
> vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
>
> + kvm_load_guest_fpu(vcpu);
> +
> for (;;) {
> if (kvm_vcpu_running(vcpu)) {
> r = vcpu_enter_guest(vcpu);
>
> <<
>
>
>
> as Rik dropped kvm_load_guest_fpu(vcpu) in vcpu_enter_guest() ..
> in case still in kvm mode, how to make sure to pkru is always the
> right one before enter guest mode, not be preempted before
> preempt_disable() after migration? :(
As you know:
1) kvm_load_guest_fpu doesn't load the guest PKRU, it keeps the
userspace PKRU.
2) the guest PKRU is only ever set in a preemption-disabled area
Thus, context switch always sees the userspace PKRU. The guest PKRU is
only set the next time vmx_vcpu_run executes.
Paolo
next prev parent reply other threads:[~2017-11-16 17:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-14 21:54 [PATCH v2 0/2] x86,kvm: move qemu/guest FPU switching out to kvm_arch_vcpu_ioctl_run riel
2017-11-14 21:54 ` [PATCH 1/2] x86,kvm: move qemu/guest FPU switching out to vcpu_run riel
2017-11-15 0:47 ` Wanpeng Li
2017-11-15 3:03 ` Rik van Riel
2017-11-15 4:33 ` Wanpeng Li
2017-11-15 14:40 ` Rik van Riel
2017-11-16 5:54 ` Wanpeng Li
2017-11-15 6:53 ` quan.xu04
2017-11-15 14:43 ` Rik van Riel
2017-11-15 15:09 ` Paolo Bonzini
2017-11-16 2:50 ` Quan Xu
2017-11-16 4:21 ` Rik van Riel
2017-11-16 5:06 ` Quan Xu
2017-11-16 10:21 ` Paolo Bonzini
2017-11-16 12:12 ` Quan Xu
2017-11-16 12:18 ` Paolo Bonzini
2017-11-16 13:35 ` Quan Xu
2017-11-16 13:39 ` Paolo Bonzini
[not found] ` <d67cef62-3165-50cd-36e8-be7c555dc79e@gmail.com>
2017-11-16 17:50 ` Paolo Bonzini [this message]
2017-11-17 2:54 ` Quan Xu
2017-11-14 21:54 ` [PATCH 2/2] x86,kvm: remove KVM emulator get_fpu / put_fpu riel
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=8396b51f-674d-74f9-e67f-026504c24631@redhat.com \
--to=pbonzini@redhat.com \
--cc=borntraeger@de.ibm.com \
--cc=david@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=quan.xu04@gmail.com \
--cc=quan.xu0@gmail.com \
--cc=riel@redhat.com \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
/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
all inboxes | Powered by JetHome®