From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Subject: [PATCH] Revert "kvm: x86: Use task structs fpu field for user"
Date: Mon, 22 Jul 2019 13:56:34 +0200 [thread overview]
Message-ID: <1563796594-25317-1-git-send-email-pbonzini@redhat.com> (raw)
This reverts commit 240c35a3783ab9b3a0afaba0dde7291295680a6b
("kvm: x86: Use task structs fpu field for user", 2018-11-06).
The commit is broken and causes QEMU's FPU state to be destroyed
when KVM_RUN is preempted.
Fixes: 240c35a3783a ("kvm: x86: Use task structs fpu field for user")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 7 ++++---
arch/x86/kvm/x86.c | 4 ++--
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0cc5b611a113..b2f1ffb937af 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -607,15 +607,16 @@ struct kvm_vcpu_arch {
/*
* QEMU userspace and the guest each have their own FPU state.
- * In vcpu_run, we switch between the user, maintained in the
- * task_struct struct, and guest FPU contexts. While running a VCPU,
- * the VCPU thread will have the guest FPU context.
+ * In vcpu_run, we switch between the user and guest FPU contexts.
+ * While running a VCPU, the VCPU thread will have the guest FPU
+ * context.
*
* Note that while the PKRU state lives inside the fpu registers,
* it is switched out separately at VMENTER and VMEXIT time. The
* "guest_fpu" state here contains the guest FPU context, with the
* host PRKU bits.
*/
+ struct fpu user_fpu;
struct fpu *guest_fpu;
u64 xcr0;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 58305cf81182..cf2afdf8facf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8270,7 +8270,7 @@ static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
{
fpregs_lock();
- copy_fpregs_to_fpstate(¤t->thread.fpu);
+ copy_fpregs_to_fpstate(&vcpu->arch.user_fpu);
/* PKRU is separately restored in kvm_x86_ops->run. */
__copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state,
~XFEATURE_MASK_PKRU);
@@ -8287,7 +8287,7 @@ static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
fpregs_lock();
copy_fpregs_to_fpstate(vcpu->arch.guest_fpu);
- copy_kernel_to_fpregs(¤t->thread.fpu.state);
+ copy_kernel_to_fpregs(&vcpu->arch.user_fpu.state);
fpregs_mark_activate();
fpregs_unlock();
--
1.8.3.1
next reply other threads:[~2019-07-22 11:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 11:56 Paolo Bonzini [this message]
2019-07-23 0:42 ` [PATCH] Revert "kvm: x86: Use task structs fpu field for user" Wanpeng Li
2019-07-23 4:31 ` Sasha Levin
2019-07-23 7:35 ` Paolo Bonzini
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