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Message-ID: <20230729005200.1057358-2-seanjc@google.com>
Date: Fri, 28 Jul 2023 17:51:56 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
Yu Zhang <yu.c.zhang@...ux.intel.com>,
Reima Ishii <ishiir@...cc.u-tokyo.ac.jp>
Subject: [PATCH v2 1/5] KVM: x86/mmu: Add helper to convert root hpa to shadow page
Add a dedicated helper for converting a root hpa to a shadow page in
anticipation of using a "dummy" root to handle the scenario where KVM
needs to load a valid shadow root (from hardware's perspective), but
the guest doesn't have a visible root to shadow. Similar to PAE roots,
the dummy root won't have an associated kvm_mmu_page and will need special
handling when finding a shadow page given a root.
Opportunistically retrieve the root shadow page in kvm_mmu_sync_roots()
*after* verifying the root is unsync (the dummy root can never be unsync).
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
arch/x86/kvm/mmu/mmu.c | 28 +++++++++++++---------------
arch/x86/kvm/mmu/spte.h | 9 +++++++++
arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
3 files changed, 23 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ec169f5c7dce..1eadfcde30be 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3574,11 +3574,7 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
if (!VALID_PAGE(*root_hpa))
return;
- /*
- * The "root" may be a special root, e.g. a PAE entry, treat it as a
- * SPTE to ensure any non-PA bits are dropped.
- */
- sp = spte_to_child_sp(*root_hpa);
+ sp = root_to_sp(*root_hpa);
if (WARN_ON(!sp))
return;
@@ -3624,7 +3620,7 @@ void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu,
&invalid_list);
if (free_active_root) {
- if (to_shadow_page(mmu->root.hpa)) {
+ if (root_to_sp(mmu->root.hpa)) {
mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list);
} else if (mmu->pae_root) {
for (i = 0; i < 4; ++i) {
@@ -3648,6 +3644,7 @@ EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);
void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu)
{
unsigned long roots_to_free = 0;
+ struct kvm_mmu_page *sp;
hpa_t root_hpa;
int i;
@@ -3662,8 +3659,8 @@ void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu)
if (!VALID_PAGE(root_hpa))
continue;
- if (!to_shadow_page(root_hpa) ||
- to_shadow_page(root_hpa)->role.guest_mode)
+ sp = root_to_sp(root_hpa);
+ if (!sp || sp->role.guest_mode)
roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i);
}
@@ -4018,7 +4015,7 @@ static bool is_unsync_root(hpa_t root)
* requirement isn't satisfied.
*/
smp_rmb();
- sp = to_shadow_page(root);
+ sp = root_to_sp(root);
/*
* PAE roots (somewhat arbitrarily) aren't backed by shadow pages, the
@@ -4048,11 +4045,12 @@ void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) {
hpa_t root = vcpu->arch.mmu->root.hpa;
- sp = to_shadow_page(root);
if (!is_unsync_root(root))
return;
+ sp = root_to_sp(root);
+
write_lock(&vcpu->kvm->mmu_lock);
mmu_sync_children(vcpu, sp, true);
write_unlock(&vcpu->kvm->mmu_lock);
@@ -4382,7 +4380,7 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
static bool is_page_fault_stale(struct kvm_vcpu *vcpu,
struct kvm_page_fault *fault)
{
- struct kvm_mmu_page *sp = to_shadow_page(vcpu->arch.mmu->root.hpa);
+ struct kvm_mmu_page *sp = root_to_sp(vcpu->arch.mmu->root.hpa);
/* Special roots, e.g. pae_root, are not backed by shadow pages. */
if (sp && is_obsolete_sp(vcpu->kvm, sp))
@@ -4564,7 +4562,7 @@ static inline bool is_root_usable(struct kvm_mmu_root_info *root, gpa_t pgd,
{
return (role.direct || pgd == root->pgd) &&
VALID_PAGE(root->hpa) &&
- role.word == to_shadow_page(root->hpa)->role.word;
+ role.word == root_to_sp(root->hpa)->role.word;
}
/*
@@ -4638,7 +4636,7 @@ static bool fast_pgd_switch(struct kvm *kvm, struct kvm_mmu *mmu,
* having to deal with PDPTEs. We may add support for 32-bit hosts/VMs
* later if necessary.
*/
- if (VALID_PAGE(mmu->root.hpa) && !to_shadow_page(mmu->root.hpa))
+ if (VALID_PAGE(mmu->root.hpa) && !root_to_sp(mmu->root.hpa))
kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT);
if (VALID_PAGE(mmu->root.hpa))
@@ -4686,7 +4684,7 @@ void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd)
*/
if (!new_role.direct)
__clear_sp_write_flooding_count(
- to_shadow_page(vcpu->arch.mmu->root.hpa));
+ root_to_sp(vcpu->arch.mmu->root.hpa));
}
EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd);
@@ -5555,7 +5553,7 @@ static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa)
* (c) KVM doesn't track previous roots for PAE paging, and the guest
* is unlikely to zap an in-use PGD.
*/
- sp = to_shadow_page(root_hpa);
+ sp = root_to_sp(root_hpa);
return !sp || is_obsolete_sp(kvm, sp);
}
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 1279db2eab44..9f8e8cda89e8 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -236,6 +236,15 @@ static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep)
return to_shadow_page(__pa(sptep));
}
+static inline struct kvm_mmu_page *root_to_sp(hpa_t root)
+{
+ /*
+ * The "root" may be a special root, e.g. a PAE entry, treat it as a
+ * SPTE to ensure any non-PA bits are dropped.
+ */
+ return spte_to_child_sp(root);
+}
+
static inline bool is_mmio_spte(u64 spte)
{
return (spte & shadow_mmio_mask) == shadow_mmio_value &&
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 512163d52194..046ac2589611 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -689,7 +689,7 @@ static inline void tdp_mmu_iter_set_spte(struct kvm *kvm, struct tdp_iter *iter,
else
#define tdp_mmu_for_each_pte(_iter, _mmu, _start, _end) \
- for_each_tdp_pte(_iter, to_shadow_page(_mmu->root.hpa), _start, _end)
+ for_each_tdp_pte(_iter, root_to_sp(_mmu->root.hpa), _start, _end)
/*
* Yield if the MMU lock is contended or this thread needs to return control
--
2.41.0.487.g6d72f3e995-goog
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