Re: [PATCH 2/5] kvm/svm: enhance MOV CR intercept handler

[Avi Kivity <avi@redhat.com>]

On 12/10/2010 03:51 PM, Andre Przywara wrote:
> Newer SVM implementations provide the GPR number in the VMCB, so
> that the emulation path is no longer necesarry to handle CR
> register access intercepts. Implement the handling in svm.c and
> use it when the info is provided.
>
> Signed-off-by: Andre Przywara<andre.przywara@amd.com>
> ---
>   arch/x86/include/asm/svm.h |    2 +
>   arch/x86/kvm/svm.c         |   91 ++++++++++++++++++++++++++++++++++++++-----
>   2 files changed, 82 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 11dbca7..589fc25 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -256,6 +256,8 @@ struct __attribute__ ((__packed__)) vmcb {
>   #define SVM_EXITINFOSHIFT_TS_REASON_JMP 38
>   #define SVM_EXITINFOSHIFT_TS_HAS_ERROR_CODE 44
>
> +#define SVM_EXITINFO_REG_MASK 0x0F
> +
>   #define	SVM_EXIT_READ_CR0 	0x000
>   #define	SVM_EXIT_READ_CR3 	0x003
>   #define	SVM_EXIT_READ_CR4 	0x004
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 298ff79..ee5f100 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2594,12 +2594,81 @@ static int emulate_on_interception(struct vcpu_svm *svm)
>   	return emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DONE;
>   }
>
> +static int cr_interception(struct vcpu_svm *svm)
> +{
> +	int reg, cr;
> +	unsigned long val;
> +	int err;
> +
> +	if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
> +		return emulate_on_interception(svm);
> +
> +	/* bit 63 is the valid bit, as not all instructions (like lmsw)
> +	   provide the information */

Please use kernel style comments:

  /*
   * text
   * text
   */

Even better, use a name for the bit, which will obviate the need for a 
comment.


-- 
error compiling committee.c: too many arguments to function