KVM: Cache pdptrs

Instead of reloading the pdptrs on every entry and exit (vmcs writes on vmx,
guest memory access on svm) extract them on demand.

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 81c68f6..1cc901e 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -120,6 +120,10 @@ enum kvm_reg {
        NR_VCPU_REGS
 };
 
+enum kvm_reg_ex {
+       VCPU_EXREG_PDPTR = NR_VCPU_REGS,
+};
+
 enum {
        VCPU_SREG_ES,
        VCPU_SREG_CS,

diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index 1ff819d..7bcc5b6 100644 (file)
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -29,4 +29,13 @@ static inline void kvm_rip_write(struct kvm_vcpu *vcpu, unsigned long val)
        kvm_register_write(vcpu, VCPU_REGS_RIP, val);
 }
 
+static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
+{
+       if (!test_bit(VCPU_EXREG_PDPTR,
+                     (unsigned long *)&vcpu->arch.regs_avail))
+               kvm_x86_ops->cache_reg(vcpu, VCPU_EXREG_PDPTR);
+
+       return vcpu->arch.pdptrs[index];
+}
+
 #endif

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 0ef5bb2..8ee67e3 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -18,6 +18,7 @@
  */
 
 #include "mmu.h"
+#include "kvm_cache_regs.h"
 
 #include <linux/kvm_host.h>
 #include <linux/types.h>
@@ -1954,6 +1955,7 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
        gfn_t root_gfn;
        struct kvm_mmu_page *sp;
        int direct = 0;
+       u64 pdptr;
 
        root_gfn = vcpu->arch.cr3 >> PAGE_SHIFT;
 
@@ -1981,11 +1983,12 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
 
                ASSERT(!VALID_PAGE(root));
                if (vcpu->arch.mmu.root_level == PT32E_ROOT_LEVEL) {
-                       if (!is_present_pte(vcpu->arch.pdptrs[i])) {
+                       pdptr = kvm_pdptr_read(vcpu, i);
+                       if (!is_present_pte(pdptr)) {
                                vcpu->arch.mmu.pae_root[i] = 0;
                                continue;
                        }
-                       root_gfn = vcpu->arch.pdptrs[i] >> PAGE_SHIFT;
+                       root_gfn = pdptr >> PAGE_SHIFT;
                } else if (vcpu->arch.mmu.root_level == 0)
                        root_gfn = 0;
                if (mmu_check_root(vcpu, root_gfn))

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 67785f6..4cb1dbf 100644 (file)
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -131,7 +131,7 @@ walk:
        pte = vcpu->arch.cr3;
 #if PTTYPE == 64
        if (!is_long_mode(vcpu)) {
-               pte = vcpu->arch.pdptrs[(addr >> 30) & 3];
+               pte = kvm_pdptr_read(vcpu, (addr >> 30) & 3);
                if (!is_present_pte(pte))
                        goto not_present;
                --walker->level;

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 522e695..7749b06 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -777,6 +777,18 @@ static void svm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
        to_svm(vcpu)->vmcb->save.rflags = rflags;
 }
 
+static void svm_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
+{
+       switch (reg) {
+       case VCPU_EXREG_PDPTR:
+               BUG_ON(!npt_enabled);
+               load_pdptrs(vcpu, vcpu->arch.cr3);
+               break;
+       default:
+               BUG();
+       }
+}
+
 static void svm_set_vintr(struct vcpu_svm *svm)
 {
        svm->vmcb->control.intercept |= 1ULL << INTERCEPT_VINTR;
@@ -2285,12 +2297,6 @@ static int handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
                }
                vcpu->arch.cr0 = svm->vmcb->save.cr0;
                vcpu->arch.cr3 = svm->vmcb->save.cr3;
-               if (is_paging(vcpu) && is_pae(vcpu) && !is_long_mode(vcpu)) {
-                       if (!load_pdptrs(vcpu, vcpu->arch.cr3)) {
-                               kvm_inject_gp(vcpu, 0);
-                               return 1;
-                       }
-               }
                if (mmu_reload) {
                        kvm_mmu_reset_context(vcpu);
                        kvm_mmu_load(vcpu);
@@ -2641,6 +2647,11 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
        svm->next_rip = 0;
 
+       if (npt_enabled) {
+               vcpu->arch.regs_avail &= ~(1 << VCPU_EXREG_PDPTR);
+               vcpu->arch.regs_dirty &= ~(1 << VCPU_EXREG_PDPTR);
+       }
+
        svm_complete_interrupts(svm);
 }
 
@@ -2749,6 +2760,7 @@ static struct kvm_x86_ops svm_x86_ops = {
        .set_gdt = svm_set_gdt,
        .get_dr = svm_get_dr,
        .set_dr = svm_set_dr,
+       .cache_reg = svm_cache_reg,
        .get_rflags = svm_get_rflags,
        .set_rflags = svm_set_rflags,
 

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 752465f..d726dec 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -161,6 +161,8 @@ static struct kvm_vmx_segment_field {
        VMX_SEGMENT_FIELD(LDTR),
 };
 
+static void ept_save_pdptrs(struct kvm_vcpu *vcpu);
+
 /*
  * Keep MSR_K6_STAR at the end, as setup_msrs() will try to optimize it
  * away by decrementing the array size.
@@ -1047,6 +1049,10 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
        case VCPU_REGS_RIP:
                vcpu->arch.regs[VCPU_REGS_RIP] = vmcs_readl(GUEST_RIP);
                break;
+       case VCPU_EXREG_PDPTR:
+               if (enable_ept)
+                       ept_save_pdptrs(vcpu);
+               break;
        default:
                break;
        }
@@ -1546,6 +1552,10 @@ static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
 
 static void ept_load_pdptrs(struct kvm_vcpu *vcpu)
 {
+       if (!test_bit(VCPU_EXREG_PDPTR,
+                     (unsigned long *)&vcpu->arch.regs_dirty))
+               return;
+
        if (is_paging(vcpu) && is_pae(vcpu) && !is_long_mode(vcpu)) {
                vmcs_write64(GUEST_PDPTR0, vcpu->arch.pdptrs[0]);
                vmcs_write64(GUEST_PDPTR1, vcpu->arch.pdptrs[1]);
@@ -1562,6 +1572,11 @@ static void ept_save_pdptrs(struct kvm_vcpu *vcpu)
                vcpu->arch.pdptrs[2] = vmcs_read64(GUEST_PDPTR2);
                vcpu->arch.pdptrs[3] = vmcs_read64(GUEST_PDPTR3);
        }
+
+       __set_bit(VCPU_EXREG_PDPTR,
+                 (unsigned long *)&vcpu->arch.regs_avail);
+       __set_bit(VCPU_EXREG_PDPTR,
+                 (unsigned long *)&vcpu->arch.regs_dirty);
 }
 
 static void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
@@ -3255,10 +3270,8 @@ static int vmx_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 
        /* Access CR3 don't cause VMExit in paging mode, so we need
         * to sync with guest real CR3. */
-       if (enable_ept && is_paging(vcpu)) {
+       if (enable_ept && is_paging(vcpu))
                vcpu->arch.cr3 = vmcs_readl(GUEST_CR3);
-               ept_save_pdptrs(vcpu);
-       }
 
        if (unlikely(vmx->fail)) {
                kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
@@ -3567,7 +3580,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 #endif
              );
 
-       vcpu->arch.regs_avail = ~((1 << VCPU_REGS_RIP) | (1 << VCPU_REGS_RSP));
+       vcpu->arch.regs_avail = ~((1 << VCPU_REGS_RIP) | (1 << VCPU_REGS_RSP)
+                                 | (1 << VCPU_EXREG_PDPTR));
        vcpu->arch.regs_dirty = 0;
 
        get_debugreg(vcpu->arch.dr6, 6);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 75e9df0..2ad8c97 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -246,6 +246,10 @@ int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
        ret = 1;
 
        memcpy(vcpu->arch.pdptrs, pdpte, sizeof(vcpu->arch.pdptrs));
+       __set_bit(VCPU_EXREG_PDPTR,
+                 (unsigned long *)&vcpu->arch.regs_avail);
+       __set_bit(VCPU_EXREG_PDPTR,
+                 (unsigned long *)&vcpu->arch.regs_dirty);
 out:
 
        return ret;
@@ -261,6 +265,10 @@ static bool pdptrs_changed(struct kvm_vcpu *vcpu)
        if (is_long_mode(vcpu) || !is_pae(vcpu))
                return false;
 
+       if (!test_bit(VCPU_EXREG_PDPTR,
+                     (unsigned long *)&vcpu->arch.regs_avail))
+               return true;
+
        r = kvm_read_guest(vcpu->kvm, vcpu->arch.cr3 & ~31u, pdpte, sizeof(pdpte));
        if (r < 0)
                goto out;