On Sat, Feb 13, 2010 at 10:51:40AM +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
>
> VMX requires a properly set instruction length VM entry field when
> trying to inject soft exception and interrupts. We have to preserve this
> state across VM save/restore to avoid breaking the re-injection of such
> events on Intel. So add it to the new VCPU event state.
>
We shouldn't re-inject soft exceptions/interrupts after migration, but
re-execute instruction instead. Instruction length field doesn't exist
on SVM and migration shouldn't expose implementation details.
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> ---
>
> Existing qemu[-kvm]-0.12 that is already prepared for 2.6.33 will need
> an update now. Whenever we actually ran into the case that
> event_exit_inst_len was evaluated by VMX, we were playing roulette with
> a high probability to crash the guest. This will not changes for already
> released 0.12.x versions.
>
> Documentation/kvm/api.txt | 2 ++
> arch/x86/include/asm/kvm.h | 3 ++-
> arch/x86/kvm/x86.c | 4 ++++
> 3 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
> index c6416a3..aa11d70 100644
> --- a/Documentation/kvm/api.txt
> +++ b/Documentation/kvm/api.txt
> @@ -686,6 +686,8 @@ struct kvm_vcpu_events {
> } nmi;
> __u32 sipi_vector;
> __u32 flags;
> + __u32 instruction_length; /* used by VMX */
> + __u32 reserved[9];
> };
>
> 4.30 KVM_SET_VCPU_EVENTS
> diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
> index f46b79f..570b6cc 100644
> --- a/arch/x86/include/asm/kvm.h
> +++ b/arch/x86/include/asm/kvm.h
> @@ -281,7 +281,8 @@ struct kvm_vcpu_events {
> } nmi;
> __u32 sipi_vector;
> __u32 flags;
> - __u32 reserved[10];
> + __u32 instruction_length; /* used by VMX */
> + __u32 reserved[9];
> };
>
> #endif /* _ASM_X86_KVM_H */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 86b739f..0cc6cfb 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2134,6 +2134,8 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
> events->nmi.pending = vcpu->arch.nmi_pending;
> events->nmi.masked = kvm_x86_ops->get_nmi_mask(vcpu);
>
> + events->instruction_length = vcpu->arch.event_exit_inst_len;
> +
> events->sipi_vector = vcpu->arch.sipi_vector;
>
> events->flags = (KVM_VCPUEVENT_VALID_NMI_PENDING
> @@ -2170,6 +2172,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
> if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR)
> vcpu->arch.sipi_vector = events->sipi_vector;
>
> + vcpu->arch.event_exit_inst_len = events->instruction_length;
> +
> vcpu_put(vcpu);
>
> return 0;
>
--
Gleb.
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