From: Andy Lutomirski <luto@amacapital.net>
To: David Matlack <dmatlack@google.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>, kvm list <kvm@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Andrew Lutomirski <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
digitaleric@google.com
Subject: Re: [PATCH 1/1] KVM: don't allow irq_fpu_usable when the VCPU's XCR0 is loaded
Date: Fri, 11 Mar 2016 13:14:20 -0800 [thread overview]
Message-ID: <CALCETrVc-GaqWC+MZm08YOUCMumzQ-TJK4h296LMtpQPdPS=0Q@mail.gmail.com> (raw)
In-Reply-To: <1457729240-3846-2-git-send-email-dmatlack@google.com>
On Fri, Mar 11, 2016 at 12:47 PM, David Matlack <dmatlack@google.com> wrote:
> From: Eric Northup <digitaleric@google.com>
>
> Add a percpu boolean, tracking whether a KVM vCPU is running on the
> host CPU. KVM will set and clear it as it loads/unloads guest XCR0.
> (Note that the rest of the guest FPU load/restore is safe, because
> kvm_load_guest_fpu and kvm_put_guest_fpu call __kernel_fpu_begin()
> and __kernel_fpu_end(), respectively.) irq_fpu_usable() will then
> also check for this percpu boolean.
Is this better than just always keeping the host's XCR0 loaded outside
if the KVM interrupts-disabled region?
--Andy
next prev parent reply other threads:[~2016-03-11 21:14 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 20:47 [PATCH 0/1] KVM: x86: using the fpu in interrupt context with a guest's xcr0 David Matlack
2016-03-11 20:47 ` [PATCH 1/1] KVM: don't allow irq_fpu_usable when the VCPU's XCR0 is loaded David Matlack
2016-03-11 21:14 ` Andy Lutomirski [this message]
2016-03-11 21:33 ` David Matlack
2016-03-14 13:17 ` Paolo Bonzini
2016-03-15 18:27 ` Andy Lutomirski
2016-03-15 19:32 ` Paolo Bonzini
2016-03-16 3:55 ` Xiao Guangrong
2016-03-16 12:01 ` Paolo Bonzini
2016-03-14 7:46 ` [PATCH 0/1] KVM: x86: using the fpu in interrupt context with a guest's xcr0 Xiao Guangrong
2016-03-15 19:01 ` David Matlack
2016-03-16 3:43 ` Xiao Guangrong
2016-03-16 3:48 ` Andy Lutomirski
2016-03-16 17:11 ` David Matlack
2016-03-16 17:09 ` David Matlack
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