From: Peter Xu <peterx@redhat.com>
Date: Tue, 12 Dec 2017 17:15:02 +0100
Subject: kvm: x86: fix WARN due to uninitialized guest FPU state
Patch-mainline: v4.15-rc5
Git-commit: 5663d8f9bbe4bf15488f7351efb61ea20fa6de06
References: bsc#1077761
------------[ cut here ]------------
Bad FPU state detected at kvm_put_guest_fpu+0xd8/0x2d0 [kvm], reinitializing FPU registers.
WARNING: CPU: 1 PID: 4594 at arch/x86/mm/extable.c:103 ex_handler_fprestore+0x88/0x90
CPU: 1 PID: 4594 Comm: qemu-system-x86 Tainted: G B OE 4.15.0-rc2+ #10
RIP: 0010:ex_handler_fprestore+0x88/0x90
Call Trace:
fixup_exception+0x4e/0x60
do_general_protection+0xff/0x270
general_protection+0x22/0x30
RIP: 0010:kvm_put_guest_fpu+0xd8/0x2d0 [kvm]
RSP: 0018:ffff8803d5627810 EFLAGS: 00010246
kvm_vcpu_reset+0x3b4/0x3c0 [kvm]
kvm_apic_accept_events+0x1c0/0x240 [kvm]
kvm_arch_vcpu_ioctl_run+0x1658/0x2fb0 [kvm]
kvm_vcpu_ioctl+0x479/0x880 [kvm]
do_vfs_ioctl+0x142/0x9a0
SyS_ioctl+0x74/0x80
do_syscall_64+0x15f/0x600
where kvm_put_guest_fpu is called without a prior kvm_load_guest_fpu.
To fix it, move kvm_load_guest_fpu to the very beginning of
kvm_arch_vcpu_ioctl_run.
Cc: stable@vger.kernel.org
Fixes: f775b13eedee2f7f3c6fdd4e90fb79090ce5d339
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Alexander Graf <agraf@suse.de>
---
arch/x86/kvm/x86.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7264,13 +7264,12 @@
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
- struct fpu *fpu = ¤t->thread.fpu;
int r;
- fpu__activate_curr(fpu);
-
kvm_sigset_activate(vcpu);
+ kvm_load_guest_fpu(vcpu);
+
if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_UNINITIALIZED)) {
if (kvm_run->immediate_exit) {
r = -EINTR;
@@ -7296,14 +7295,12 @@
}
}
- kvm_load_guest_fpu(vcpu);
-
if (unlikely(vcpu->arch.complete_userspace_io)) {
int (*cui)(struct kvm_vcpu *) = vcpu->arch.complete_userspace_io;
vcpu->arch.complete_userspace_io = NULL;
r = cui(vcpu);
if (r <= 0)
- goto out_fpu;
+ goto out;
} else
WARN_ON(vcpu->arch.pio.count || vcpu->mmio_needed);
@@ -7312,9 +7309,8 @@
else
r = vcpu_run(vcpu);
-out_fpu:
- kvm_put_guest_fpu(vcpu);
out:
+ kvm_put_guest_fpu(vcpu);
post_kvm_run_save(vcpu);
kvm_sigset_deactivate(vcpu);