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SubjectRe: [PATCH 08/12] kvm/svm: cache nested intercepts
On 07/29/2009 03:56 PM, Joerg Roedel wrote:
> Signed-off-by: Joerg Roedel<joerg.roedel@amd.com>
> ---
> arch/x86/kvm/svm.c | 30 +++++++++++++++++++++++-------
> 1 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 31467b1..9192c9a 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -86,6 +86,15 @@ struct nested_state {
>
> /* gpa pointers to the real vectors */
> u64 vmcb_msrpm;
> +
> + /* cache for intercepts of the guest */
> + u16 intercept_cr_read;
> + u16 intercept_cr_write;
> + u16 intercept_dr_read;
> + u16 intercept_dr_write;
> + u32 intercept_exceptions;
> + u64 intercept;
> +
> };
>
> struct vcpu_svm {
> @@ -1459,7 +1468,6 @@ static int nested_svm_exit_handled_real(struct vcpu_svm *svm,
> void *arg2,
> void *opaque)
> {
> - struct vmcb *nested_vmcb = (struct vmcb *)arg1;
> bool kvm_overrides = *(bool *)opaque;
> u32 exit_code = svm->vmcb->control.exit_code;
>
> @@ -1486,38 +1494,38 @@ static int nested_svm_exit_handled_real(struct vcpu_svm *svm,
> switch (exit_code) {
> case SVM_EXIT_READ_CR0 ... SVM_EXIT_READ_CR8: {
> u32 cr_bits = 1<< (exit_code - SVM_EXIT_READ_CR0);
> - if (nested_vmcb->control.intercept_cr_read& cr_bits)
> + if (svm->nested.intercept_cr_read& cr_bits)
> return 1;
> break;
> }
> case SVM_EXIT_WRITE_CR0 ... SVM_EXIT_WRITE_CR8: {
> u32 cr_bits = 1<< (exit_code - SVM_EXIT_WRITE_CR0);
> - if (nested_vmcb->control.intercept_cr_write& cr_bits)
> + if (svm->nested.intercept_cr_write& cr_bits)
> return 1;
> break;
> }
> case SVM_EXIT_READ_DR0 ... SVM_EXIT_READ_DR7: {
> u32 dr_bits = 1<< (exit_code - SVM_EXIT_READ_DR0);
> - if (nested_vmcb->control.intercept_dr_read& dr_bits)
> + if (svm->nested.intercept_dr_read& dr_bits)
> return 1;
> break;
> }
> case SVM_EXIT_WRITE_DR0 ... SVM_EXIT_WRITE_DR7: {
> u32 dr_bits = 1<< (exit_code - SVM_EXIT_WRITE_DR0);
> - if (nested_vmcb->control.intercept_dr_write& dr_bits)
> + if (svm->nested.intercept_dr_write& dr_bits)
> return 1;
> break;
> }
> case SVM_EXIT_EXCP_BASE ... SVM_EXIT_EXCP_BASE + 0x1f: {
> u32 excp_bits = 1<< (exit_code - SVM_EXIT_EXCP_BASE);
> - if (nested_vmcb->control.intercept_exceptions& excp_bits)
> + if (svm->nested.intercept_exceptions& excp_bits)
> return 1;
> break;
> }
> default: {
> u64 exit_bits = 1ULL<< (exit_code - SVM_EXIT_INTR);
> nsvm_printk("exit code: 0x%x\n", exit_code);
> - if (nested_vmcb->control.intercept& exit_bits)
> + if (svm->nested.intercept& exit_bits)
> return 1;
> }
> }
> @@ -1808,6 +1816,14 @@ static int nested_svm_vmrun(struct vcpu_svm *svm, void *arg1,
>
> svm->nested.vmcb_msrpm = nested_vmcb->control.msrpm_base_pa;
>
> + /* cache intercepts */
> + svm->nested.intercept_cr_read = nested_vmcb->control.intercept_cr_read;
> + svm->nested.intercept_cr_write = nested_vmcb->control.intercept_cr_write;
> + svm->nested.intercept_dr_read = nested_vmcb->control.intercept_dr_read;
> + svm->nested.intercept_dr_write = nested_vmcb->control.intercept_dr_write;
> + svm->nested.intercept_exceptions = nested_vmcb->control.intercept_exceptions;
> + svm->nested.intercept = nested_vmcb->control.intercept;
> +
> force_new_asid(&svm->vcpu);
> svm->vmcb->control.exit_int_info = nested_vmcb->control.exit_int_info;
> svm->vmcb->control.exit_int_info_err = nested_vmcb->control.exit_int_info_err;
>

I don't see the benefit of this patch. Accessing the cache is just as
expensive as accessing the real vmcb.

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



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