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Subject[PATCH 28/48] KVM: Cache pdptrs
Date
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>
---
arch/x86/include/asm/kvm_host.h | 4 ++++
arch/x86/kvm/kvm_cache_regs.h | 9 +++++++++
arch/x86/kvm/mmu.c | 7 +++++--
arch/x86/kvm/paging_tmpl.h | 2 +-
arch/x86/kvm/svm.c | 24 ++++++++++++++++++------
arch/x86/kvm/vmx.c | 22 ++++++++++++++++++----
arch/x86/kvm/x86.c | 8 ++++++++
7 files changed, 63 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 81c68f6..1cc901e 100644
--- 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
--- 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
--- 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
--- 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 14a98ab..0710e45 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -780,6 +780,18 @@ 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;
@@ -2286,12 +2298,6 @@ 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);
@@ -2642,6 +2648,11 @@ 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);
}

@@ -2750,6 +2761,7 @@ 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
--- 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
--- 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;
--
1.6.3.3


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