Re: [PATCH 08/12] kvm/svm: cache nested intercepts

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On 07/29/2009 03:56 PM, Joerg Roedel wrote:
Signed-off-by: Joerg Roedel<joerg.roedel@xxxxxxx>
---
  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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