KVM: SVM: Optimize nested svm msrpm merging

[net-next-2.6.git] / arch / x86 / kvm / svm.c

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a079550d3886fbe54cc010858024752a815f50d0..45a287e51e1827445e764064e7e47c5381c866b0 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -93,6 +93,9 @@ struct nested_state {
 
 };
 
+#define MSRPM_OFFSETS  16
+static u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
+
 struct vcpu_svm {
        struct kvm_vcpu vcpu;
        struct vmcb *vmcb;
@@ -510,6 +513,49 @@ static void svm_vcpu_init_msrpm(u32 *msrpm)
        }
 }
 
+static void add_msr_offset(u32 offset)
+{
+       int i;
+
+       for (i = 0; i < MSRPM_OFFSETS; ++i) {
+
+               /* Offset already in list? */
+               if (msrpm_offsets[i] == offset)
+                       return;
+
+               /* Slot used by another offset? */
+               if (msrpm_offsets[i] != MSR_INVALID)
+                       continue;
+
+               /* Add offset to list */
+               msrpm_offsets[i] = offset;
+
+               return;
+       }
+
+       /*
+        * If this BUG triggers the msrpm_offsets table has an overflow. Just
+        * increase MSRPM_OFFSETS in this case.
+        */
+       BUG();
+}
+
+static void init_msrpm_offsets(void)
+{
+       int i;
+
+       memset(msrpm_offsets, 0xff, sizeof(msrpm_offsets));
+
+       for (i = 0; direct_access_msrs[i].index != MSR_INVALID; i++) {
+               u32 offset;
+
+               offset = svm_msrpm_offset(direct_access_msrs[i].index);
+               BUG_ON(offset == MSR_INVALID);
+
+               add_msr_offset(offset);
+       }
+}
+
 static void svm_enable_lbrv(struct vcpu_svm *svm)
 {
        u32 *msrpm = svm->msrpm;
@@ -548,6 +594,8 @@ static __init int svm_hardware_setup(void)
        memset(iopm_va, 0xff, PAGE_SIZE * (1 << IOPM_ALLOC_ORDER));
        iopm_base = page_to_pfn(iopm_pages) << PAGE_SHIFT;
 
+       init_msrpm_offsets();
+
        if (boot_cpu_has(X86_FEATURE_NX))
                kvm_enable_efer_bits(EFER_NX);
 
@@ -811,6 +859,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
        svm_vcpu_init_msrpm(svm->msrpm);
 
        svm->nested.msrpm = page_address(nested_msrpm_pages);
+       svm_vcpu_init_msrpm(svm->nested.msrpm);
 
        svm->vmcb = page_address(page);
        clear_page(svm->vmcb);
@@ -1888,20 +1937,33 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
 
 static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
 {
-       u32 *nested_msrpm;
-       struct page *page;
+       /*
+        * This function merges the msr permission bitmaps of kvm and the
+        * nested vmcb. It is omptimized in that it only merges the parts where
+        * the kvm msr permission bitmap may contain zero bits
+        */
        int i;
 
-       nested_msrpm = nested_svm_map(svm, svm->nested.vmcb_msrpm, &page);
-       if (!nested_msrpm)
-               return false;
+       if (!(svm->nested.intercept & (1ULL << INTERCEPT_MSR_PROT)))
+               return true;
 
-       for (i = 0; i < PAGE_SIZE * (1 << MSRPM_ALLOC_ORDER) / 4; i++)
-               svm->nested.msrpm[i] = svm->msrpm[i] | nested_msrpm[i];
+       for (i = 0; i < MSRPM_OFFSETS; i++) {
+               u32 value, p;
+               u64 offset;
 
-       svm->vmcb->control.msrpm_base_pa = __pa(svm->nested.msrpm);
+               if (msrpm_offsets[i] == 0xffffffff)
+                       break;
 
-       nested_svm_unmap(page);
+               offset = svm->nested.vmcb_msrpm + msrpm_offsets[i];
+               p      = msrpm_offsets[i] / 4;
+
+               if (kvm_read_guest(svm->vcpu.kvm, offset, &value, 4))
+                       return false;
+
+               svm->nested.msrpm[p] = svm->msrpm[p] | value;
+       }
+
+       svm->vmcb->control.msrpm_base_pa = __pa(svm->nested.msrpm);
 
        return true;
 }