Commit ade61e28 authored by Junaid Shahid's avatar Junaid Shahid Committed by Paolo Bonzini

kvm: x86: Skip TLB flush on fast CR3 switch when indicated by guest

When PCIDs are enabled, the MSb of the source operand for a MOV-to-CR3
instruction indicates that the TLB doesn't need to be flushed.

This change enables this optimization for MOV-to-CR3s in the guest
that have been intercepted by KVM for shadow paging and are handled
within the fast CR3 switch path.
Signed-off-by: default avatarJunaid Shahid <junaids@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent eb4b248e
......@@ -1318,7 +1318,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u64 error_code,
void *insn, int insn_len);
void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid);
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3);
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush);
void kvm_enable_tdp(void);
void kvm_disable_tdp(void);
......
......@@ -4037,7 +4037,8 @@ static void nonpaging_init_context(struct kvm_vcpu *vcpu,
}
static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
union kvm_mmu_page_role new_role)
union kvm_mmu_page_role new_role,
bool skip_tlb_flush)
{
struct kvm_mmu *mmu = &vcpu->arch.mmu;
......@@ -4070,7 +4071,9 @@ static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
kvm_make_request(KVM_REQ_LOAD_CR3, vcpu);
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
kvm_x86_ops->tlb_flush(vcpu, true);
if (!skip_tlb_flush)
kvm_x86_ops->tlb_flush(vcpu, true);
__clear_sp_write_flooding_count(
page_header(mmu->root_hpa));
......@@ -4082,15 +4085,17 @@ static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
}
static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3,
union kvm_mmu_page_role new_role)
union kvm_mmu_page_role new_role,
bool skip_tlb_flush)
{
if (!fast_cr3_switch(vcpu, new_cr3, new_role))
if (!fast_cr3_switch(vcpu, new_cr3, new_role, skip_tlb_flush))
kvm_mmu_free_roots(vcpu, false);
}
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3)
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush)
{
__kvm_mmu_new_cr3(vcpu, new_cr3, kvm_mmu_calc_root_page_role(vcpu));
__kvm_mmu_new_cr3(vcpu, new_cr3, kvm_mmu_calc_root_page_role(vcpu),
skip_tlb_flush);
}
EXPORT_SYMBOL_GPL(kvm_mmu_new_cr3);
......@@ -4733,7 +4738,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
union kvm_mmu_page_role root_page_role =
kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty);
__kvm_mmu_new_cr3(vcpu, new_eptp, root_page_role);
__kvm_mmu_new_cr3(vcpu, new_eptp, root_page_role, false);
context->shadow_root_level = PT64_ROOT_4LEVEL;
context->nx = true;
......@@ -5196,11 +5201,16 @@ void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid)
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
}
if (VALID_PAGE(mmu->prev_root.hpa) &&
pcid == kvm_get_pcid(vcpu, mmu->prev_root.cr3))
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
++vcpu->stat.invlpg;
/*
* Mappings not reachable via the current cr3 will be synced when
* switching to that cr3, so nothing needs to be done here for them.
* Mappings not reachable via the current cr3 or the prev_root.cr3 will
* be synced when switching to that cr3, so nothing needs to be done
* here for them.
*/
}
EXPORT_SYMBOL_GPL(kvm_mmu_invpcid_gva);
......
......@@ -8819,10 +8819,14 @@ static int handle_invpcid(struct kvm_vcpu *vcpu)
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
}
if (kvm_get_pcid(vcpu, vcpu->arch.mmu.prev_root.cr3)
== operand.pcid)
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
/*
* If the current cr3 does not use the given PCID, then nothing
* needs to be done here because a resync will happen anyway
* before switching to any other CR3.
* If neither the current cr3 nor the prev_root.cr3 use the
* given PCID, then nothing needs to be done here because a
* resync will happen anyway before switching to any other CR3.
*/
return kvm_skip_emulated_instruction(vcpu);
......@@ -11434,7 +11438,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
}
if (!nested_ept)
kvm_mmu_new_cr3(vcpu, cr3);
kvm_mmu_new_cr3(vcpu, cr3, false);
vcpu->arch.cr3 = cr3;
__set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
......
......@@ -847,16 +847,21 @@ EXPORT_SYMBOL_GPL(kvm_set_cr4);
int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
{
bool skip_tlb_flush = false;
#ifdef CONFIG_X86_64
bool pcid_enabled = kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE);
if (pcid_enabled)
if (pcid_enabled) {
skip_tlb_flush = cr3 & CR3_PCID_INVD;
cr3 &= ~CR3_PCID_INVD;
}
#endif
if (cr3 == kvm_read_cr3(vcpu) && !pdptrs_changed(vcpu)) {
kvm_mmu_sync_roots(vcpu);
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
if (!skip_tlb_flush)
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
return 0;
}
......@@ -867,7 +872,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
return 1;
kvm_mmu_new_cr3(vcpu, cr3);
kvm_mmu_new_cr3(vcpu, cr3, skip_tlb_flush);
vcpu->arch.cr3 = cr3;
__set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
......
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