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Message-Id: <20190725114938.3976-4-vkuznets@redhat.com>
Date: Thu, 25 Jul 2019 13:49:38 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: stable@...r.kernel.org
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>
Subject: [PATCH stable-5.1 3/3] Revert "kvm: x86: Use task structs fpu field for user"
From: Paolo Bonzini <pbonzini@...hat.com>
[ Upstream commit ec269475cba7bcdd1eb8fdf8e87f4c6c81a376fe ]
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@...r.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@...hat.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 c79abe7ca093..564729a4a25c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -609,15 +609,16 @@ 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 37028ea85d4c..aede8fa2ea9a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8172,7 +8172,7 @@ static int complete_emulated_mmio(struct kvm_vcpu *vcpu)
static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
{
preempt_disable();
- 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);
@@ -8185,7 +8185,7 @@ static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
{
preempt_disable();
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);
preempt_enable();
++vcpu->stat.fpu_reload;
trace_kvm_fpu(0);
--
2.20.1
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