From: Paolo Bonzini <pbonzini@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, "Liu, Jing2" <jing2.liu@intel.com>,
"Bae, Chang Seok" <chang.seok.bae@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Arjan van de Ven <arjan@linux.intel.com>,
kvm@vger.kernel.org, "Nakajima, Jun" <jun.nakajima@intel.com>,
Sean Christopherson <seanjc@google.com>
Subject: Re: [patch 3/4] x86/kvm: Convert FPU handling to a single swap buffer
Date: Mon, 18 Oct 2021 13:55:53 +0200 [thread overview]
Message-ID: <b1c49069-437c-7aa6-531d-6651dad72015@redhat.com> (raw)
In-Reply-To: <20211017152048.666354328@linutronix.de>
On 17/10/21 19:03, Thomas Gleixner wrote:
> */
> - fpu_swap_kvm_fpu(vcpu->arch.user_fpu, vcpu->arch.guest_fpu,
> - ~XFEATURE_MASK_PKRU);
> + fpu_swap_kvm_fpstate(&vcpu->arch.guest_fpu, true, ~XFEATURE_MASK_PKRU);
> trace_kvm_fpu(1);
> }
>
> /* When vcpu_run ends, restore user space FPU context. */
> static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
> {
> - /*
> - * Guests with protected state have guest_fpu == NULL which makes
> - * swap only restore the host state.
> - */
> - fpu_swap_kvm_fpu(vcpu->arch.guest_fpu, vcpu->arch.user_fpu, ~0ULL);
> + fpu_swap_kvm_fpstate(&vcpu->arch.guest_fpu, false, ~0ULL);
The restore mask can be ~XFEATURE_MASK_PKRU in this case tool this way
it's constant and you can drop the third argument to the function.
Also perhaps it could be useful to add an
if (WARN_ON_ONCE(cur_fps->is_guest == enter_guest))
return;
at the top of fpu_swap_kvm_fpstate, since the is_guest member (at least
for now?) is only used for such kind of assertion.
Paolo
next prev parent reply other threads:[~2021-10-18 11:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-17 17:03 [patch 0/4] x86/fpu/kvm: Sanitize the FPU guest/user handling Thomas Gleixner
2021-10-17 17:03 ` [patch 1/4] x86/fpu: Prepare for sanitizing KVM FPU code Thomas Gleixner
2021-10-17 17:03 ` [patch 2/4] x86/fpu: Provide infrastructure for KVM FPU cleanup Thomas Gleixner
2021-10-17 17:03 ` [patch 3/4] x86/kvm: Convert FPU handling to a single swap buffer Thomas Gleixner
2021-10-18 11:55 ` Paolo Bonzini [this message]
2021-10-17 17:03 ` [patch 4/4] x86/fpu: Remove old KVM FPU interface Thomas Gleixner
2021-10-19 19:43 ` [patch 0/4] x86/fpu/kvm: Sanitize the FPU guest/user handling Bae, Chang Seok
2021-10-20 9:19 ` Paolo Bonzini
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