Re: [PATCH v2 2/3] KVM: x86: make exception_class() and exception_type() globally visible

From: Sean Christopherson
Date: Wed Aug 28 2019 - 14:35:26 EST


On Wed, Aug 28, 2019 at 05:02:57PM +0000, Jan Dakinevich wrote:
> exception_type() function was moved for upcoming sanity check in
> emulation code. exceptions_class() function is not supposed to be used
> right now, but it was moved as well to keep things together.

Doh, I didn't realize exception_type() was confined to x86.c when I
suggested the sanity check. It'd probably be better to add the check
in x86_emulate_instruction and forego this patch, e.g.:

if (ctxt->have_exception) {
WARN_ON_ONCE(...);
inject_emulated_exception(vcpu));
return EMULATE_DONE;
}

Arguably we shouldn't WARN on an unexpected vector until we actually try
to inject it anyways.

Sorry for the thrash.

>
> Cc: Denis Lunev <den@xxxxxxxxxxxxx>
> Cc: Roman Kagan <rkagan@xxxxxxxxxxxxx>
> Cc: Denis Plotnikov <dplotnikov@xxxxxxxxxxxxx>
> Signed-off-by: Jan Dakinevich <jan.dakinevich@xxxxxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 46 ----------------------------------------------
> arch/x86/kvm/x86.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+), 46 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 903fb7c..2b69ae0 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -364,52 +364,6 @@ asmlinkage __visible void kvm_spurious_fault(void)
> }
> EXPORT_SYMBOL_GPL(kvm_spurious_fault);
>
> -#define EXCPT_BENIGN 0
> -#define EXCPT_CONTRIBUTORY 1
> -#define EXCPT_PF 2
> -
> -static int exception_class(int vector)
> -{
> - switch (vector) {
> - case PF_VECTOR:
> - return EXCPT_PF;
> - case DE_VECTOR:
> - case TS_VECTOR:
> - case NP_VECTOR:
> - case SS_VECTOR:
> - case GP_VECTOR:
> - return EXCPT_CONTRIBUTORY;
> - default:
> - break;
> - }
> - return EXCPT_BENIGN;
> -}
> -
> -#define EXCPT_FAULT 0
> -#define EXCPT_TRAP 1
> -#define EXCPT_ABORT 2
> -#define EXCPT_INTERRUPT 3
> -
> -static int exception_type(int vector)
> -{
> - unsigned int mask;
> -
> - if (WARN_ON(vector > 31 || vector == NMI_VECTOR))
> - return EXCPT_INTERRUPT;
> -
> - mask = 1 << vector;
> -
> - /* #DB is trap, as instruction watchpoints are handled elsewhere */
> - if (mask & ((1 << DB_VECTOR) | (1 << BP_VECTOR) | (1 << OF_VECTOR)))
> - return EXCPT_TRAP;
> -
> - if (mask & ((1 << DF_VECTOR) | (1 << MC_VECTOR)))
> - return EXCPT_ABORT;
> -
> - /* Reserved exceptions will result in fault */
> - return EXCPT_FAULT;
> -}
> -
> void kvm_deliver_exception_payload(struct kvm_vcpu *vcpu)
> {
> unsigned nr = vcpu->arch.exception.nr;
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index b5274e2..2b66347 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -369,4 +369,50 @@ static inline bool kvm_pat_valid(u64 data)
> void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu);
> void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu);
>
> +#define EXCPT_BENIGN 0
> +#define EXCPT_CONTRIBUTORY 1
> +#define EXCPT_PF 2
> +
> +static inline int exception_class(int vector)
> +{
> + switch (vector) {
> + case PF_VECTOR:
> + return EXCPT_PF;
> + case DE_VECTOR:
> + case TS_VECTOR:
> + case NP_VECTOR:
> + case SS_VECTOR:
> + case GP_VECTOR:
> + return EXCPT_CONTRIBUTORY;
> + default:
> + break;
> + }
> + return EXCPT_BENIGN;
> +}
> +
> +#define EXCPT_FAULT 0
> +#define EXCPT_TRAP 1
> +#define EXCPT_ABORT 2
> +#define EXCPT_INTERRUPT 3
> +
> +static inline int exception_type(int vector)
> +{
> + unsigned int mask;
> +
> + if (WARN_ON(vector > 31 || vector == NMI_VECTOR))
> + return EXCPT_INTERRUPT;
> +
> + mask = 1 << vector;
> +
> + /* #DB is trap, as instruction watchpoints are handled elsewhere */
> + if (mask & ((1 << DB_VECTOR) | (1 << BP_VECTOR) | (1 << OF_VECTOR)))
> + return EXCPT_TRAP;
> +
> + if (mask & ((1 << DF_VECTOR) | (1 << MC_VECTOR)))
> + return EXCPT_ABORT;
> +
> + /* Reserved exceptions will result in fault */
> + return EXCPT_FAULT;
> +}
> +
> #endif
> --
> 2.1.4
>