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authorWanpeng Li <wanpeng.li@hotmail.com>2017-07-20 01:11:54 -0700
committerRadim Krčmář <rkrcmar@redhat.com>2017-07-20 17:00:00 +0200
commitf244deed7a254b4a61333e6886575ce0102e8356 (patch)
treeda8046fc368f57164a8816340465955b5673f3fb /arch/x86
parentc2ce3f5d89d57301e2756ac325fe2ebc33bfec30 (diff)
KVM: VMX: Fix invalid guest state detection after task-switch emulation
This can be reproduced by EPT=1, unrestricted_guest=N, emulate_invalid_state=Y or EPT=0, the trace of kvm-unit-tests/taskswitch2.flat is like below, it tries to emulate invalid guest state task-switch: kvm_exit: reason TASK_SWITCH rip 0x0 info 40000058 0 kvm_emulate_insn: 42000:0:0f 0b (0x2) kvm_emulate_insn: 42000:0:0f 0b (0x2) failed kvm_inj_exception: #UD (0x0) kvm_entry: vcpu 0 kvm_exit: reason TASK_SWITCH rip 0x0 info 40000058 0 kvm_emulate_insn: 42000:0:0f 0b (0x2) kvm_emulate_insn: 42000:0:0f 0b (0x2) failed kvm_inj_exception: #UD (0x0) ...................... It appears that the task-switch emulation updates rflags (and vm86 flag) only after the segments are loaded, causing vmx->emulation_required to be set, when in fact invalid guest state emulation is not needed. This patch fixes it by updating vmx->emulation_required after the rflags (and vm86 flag) is updated in task-switch emulation. Thanks Radim for moving the update to vmx__set_flags and adding Paolo's suggestion for the check. Suggested-by: Nadav Amit <nadav.amit@gmail.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/vmx.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 791c018a0034..29fd8af5c347 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2327,6 +2327,11 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
__vmx_load_host_state(to_vmx(vcpu));
}
+static bool emulation_required(struct kvm_vcpu *vcpu)
+{
+ return emulate_invalid_guest_state && !guest_state_valid(vcpu);
+}
+
static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu);
/*
@@ -2364,6 +2369,8 @@ static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
{
+ unsigned long old_rflags = vmx_get_rflags(vcpu);
+
__set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail);
to_vmx(vcpu)->rflags = rflags;
if (to_vmx(vcpu)->rmode.vm86_active) {
@@ -2371,6 +2378,9 @@ static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
rflags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM;
}
vmcs_writel(GUEST_RFLAGS, rflags);
+
+ if ((old_rflags ^ to_vmx(vcpu)->rflags) & X86_EFLAGS_VM)
+ to_vmx(vcpu)->emulation_required = emulation_required(vcpu);
}
static u32 vmx_get_pkru(struct kvm_vcpu *vcpu)
@@ -3858,11 +3868,6 @@ static __init int alloc_kvm_area(void)
return 0;
}
-static bool emulation_required(struct kvm_vcpu *vcpu)
-{
- return emulate_invalid_guest_state && !guest_state_valid(vcpu);
-}
-
static void fix_pmode_seg(struct kvm_vcpu *vcpu, int seg,
struct kvm_segment *save)
{