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Subject[PATCH 1/3] KVM: x86: introduce kvm_mmu_invalidate_gva
Date
Wrap the combination of mmu->invlpg and kvm_x86_ops->tlb_flush_gva
into a new function. This function also lets us specify the host PGD to
invalidate and also the MMU, both of which will be useful in fixing and
simplifying kvm_inject_emulated_page_fault.

A nested guest's MMU however has g_context->invlpg == NULL. Instead of
setting it to nonpaging_invlpg, make kvm_mmu_invalidate_gva the only
entry point to mmu->invlpg and make a NULL invlpg pointer equivalent
to nonpaging_invlpg, saving a retpoline.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/kvm/mmu/mmu.c | 71 +++++++++++++++++++++------------
2 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 328b1765ff76..f6a1ece1bb4a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1506,6 +1506,8 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
void *insn, int insn_len);
void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
+void kvm_mmu_invalidate_gva(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
+ gva_t gva, unsigned long root_hpa);
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, bool skip_tlb_flush);

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 560e85ebdf22..e26c9a583e75 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2153,10 +2153,6 @@ static int nonpaging_sync_page(struct kvm_vcpu *vcpu,
return 0;
}

-static void nonpaging_invlpg(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root)
-{
-}
-
static void nonpaging_update_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp, u64 *spte,
const void *pte)
@@ -4237,7 +4233,7 @@ static void nonpaging_init_context(struct kvm_vcpu *vcpu,
context->page_fault = nonpaging_page_fault;
context->gva_to_gpa = nonpaging_gva_to_gpa;
context->sync_page = nonpaging_sync_page;
- context->invlpg = nonpaging_invlpg;
+ context->invlpg = NULL;
context->update_pte = nonpaging_update_pte;
context->root_level = 0;
context->shadow_root_level = PT32E_ROOT_LEVEL;
@@ -4928,7 +4924,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
context->mmu_role.as_u64 = new_role.as_u64;
context->page_fault = kvm_tdp_page_fault;
context->sync_page = nonpaging_sync_page;
- context->invlpg = nonpaging_invlpg;
+ context->invlpg = NULL;
context->update_pte = nonpaging_update_pte;
context->shadow_root_level = kvm_x86_ops->get_tdp_level(vcpu);
context->direct_map = true;
@@ -5096,6 +5092,12 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
g_context->get_pdptr = kvm_pdptr_read;
g_context->inject_page_fault = kvm_inject_page_fault;

+ /*
+ * L2 page tables are never shadowed, so there is no need to sync
+ * SPTEs.
+ */
+ g_context->invlpg = NULL;
+
/*
* Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using
* L1's nested page tables (e.g. EPT12). The nested translation
@@ -5497,37 +5499,54 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
}
EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);

-void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
+void kvm_mmu_invalidate_gva(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
+ gva_t gva, unsigned long root_hpa)
{
- struct kvm_mmu *mmu = vcpu->arch.mmu;
int i;

- /* INVLPG on a * non-canonical address is a NOP according to the SDM. */
- if (is_noncanonical_address(gva, vcpu))
+ /* It's actually a GPA for vcpu->arch.guest_mmu. */
+ if (mmu != &vcpu->arch.guest_mmu) {
+ /* INVLPG on a non-canonical address is a NOP according to the SDM. */
+ if (is_noncanonical_address(gva, vcpu))
+ return;
+
+ kvm_x86_ops->tlb_flush_gva(vcpu, gva);
+ }
+
+ if (!mmu->invlpg)
return;

- mmu->invlpg(vcpu, gva, mmu->root_hpa);
+ if (root_hpa == INVALID_PAGE) {
+ mmu->invlpg(vcpu, gva, mmu->root_hpa);

- /*
- * INVLPG is required to invalidate any global mappings for the VA,
- * irrespective of PCID. Since it would take us roughly similar amount
- * of work to determine whether any of the prev_root mappings of the VA
- * is marked global, or to just sync it blindly, so we might as well
- * just always sync it.
- *
- * Mappings not reachable via the current cr3 or the prev_roots will be
- * synced when switching to that cr3, so nothing needs to be done here
- * for them.
- */
- for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
- if (VALID_PAGE(mmu->prev_roots[i].hpa))
- mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
+ /*
+ * INVLPG is required to invalidate any global mappings for the VA,
+ * irrespective of PCID. Since it would take us roughly similar amount
+ * of work to determine whether any of the prev_root mappings of the VA
+ * is marked global, or to just sync it blindly, so we might as well
+ * just always sync it.
+ *
+ * Mappings not reachable via the current cr3 or the prev_roots will be
+ * synced when switching to that cr3, so nothing needs to be done here
+ * for them.
+ */
+ for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
+ if (VALID_PAGE(mmu->prev_roots[i].hpa))
+ mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
+ } else {
+ mmu->invlpg(vcpu, gva, root_hpa);
+ }
+}
+EXPORT_SYMBOL_GPL(kvm_mmu_invalidate_gva);

- kvm_x86_ops->tlb_flush_gva(vcpu, gva);
+void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
+{
+ kvm_mmu_invalidate_gva(vcpu, vcpu->arch.mmu, gva, INVALID_PAGE);
++vcpu->stat.invlpg;
}
EXPORT_SYMBOL_GPL(kvm_mmu_invlpg);

+
void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid)
{
struct kvm_mmu *mmu = vcpu->arch.mmu;
--
2.18.2

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