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Subject[PATCH 12/22] kvm: mmu: Allocate struct kvm_mmu_pages for all pages in TDP MMU
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Attach struct kvm_mmu_pages to every page in the TDP MMU to track
metadata, facilitate NX reclaim, and enable inproved parallelism of MMU
operations in future patches.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/include/asm/kvm_host.h | 4 ++++
arch/x86/kvm/mmu/tdp_mmu.c | 13 ++++++++++---
2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9ce6b35ecb33a..a76bcb51d43d8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -972,7 +972,11 @@ struct kvm_arch {
* operations.
*/
bool tdp_mmu_enabled;
+
+ /* List of struct tdp_mmu_pages being used as roots */
struct list_head tdp_mmu_roots;
+ /* List of struct tdp_mmu_pages not being used as roots */
+ struct list_head tdp_mmu_pages;
};

struct kvm_vm_stat {
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index a3bcee6bf30e8..557e780bdf9f9 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -30,6 +30,7 @@ void kvm_mmu_init_tdp_mmu(struct kvm *kvm)
kvm->arch.tdp_mmu_enabled = true;

INIT_LIST_HEAD(&kvm->arch.tdp_mmu_roots);
+ INIT_LIST_HEAD(&kvm->arch.tdp_mmu_pages);
}

void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm)
@@ -244,6 +245,7 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
bool is_leaf = is_present && is_last_spte(new_spte, level);
bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte);
u64 *pt;
+ struct kvm_mmu_page *sp;
u64 old_child_spte;
int i;

@@ -309,6 +311,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
*/
if (was_present && !was_leaf && (pfn_changed || !is_present)) {
pt = spte_to_child_pt(old_spte, level);
+ sp = sptep_to_sp(pt);
+
+ list_del(&sp->link);

for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
old_child_spte = *(pt + i);
@@ -322,6 +327,7 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
KVM_PAGES_PER_HPAGE(level));

free_page((unsigned long)pt);
+ kmem_cache_free(mmu_page_header_cache, sp);
}
}

@@ -474,8 +480,7 @@ int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, int write, int map_writable,
bool prefault, bool account_disallowed_nx_lpage)
{
struct tdp_iter iter;
- struct kvm_mmu_memory_cache *pf_pt_cache =
- &vcpu->arch.mmu_shadow_page_cache;
+ struct kvm_mmu_page *sp;
u64 *child_pt;
u64 new_spte;
int ret;
@@ -520,7 +525,9 @@ int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, int write, int map_writable,
}

if (!is_shadow_present_pte(iter.old_spte)) {
- child_pt = kvm_mmu_memory_cache_alloc(pf_pt_cache);
+ sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level);
+ list_add(&sp->link, &vcpu->kvm->arch.tdp_mmu_pages);
+ child_pt = sp->spt;
clear_page(child_pt);
new_spte = make_nonleaf_spte(child_pt,
!shadow_accessed_mask);
--
2.28.0.709.gb0816b6eb0-goog
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