From: Paolo Bonzini pbonzini@redhat.com
commit ec269475cba7bcdd1eb8fdf8e87f4c6c81a376fe upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/kvm_host.h | 7 ++++--- arch/x86/kvm/x86.c | 4 ++-- 2 files changed, 6 insertions(+), 5 deletions(-)
--- 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; --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8172,7 +8172,7 @@ static int complete_emulated_mmio(struct 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 { 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);