[PATCH v2 11/20] kvm: x86/mmu: Allocate struct kvm_mmu_pages for all pages in TDP MMU

From: Ben Gardon
Date: Wed Oct 14 2020 - 14:27:32 EST


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@xxxxxxxxxx>
---
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 e0ec1dd271a32..2568dcd134156 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -989,7 +989,11 @@ 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 f92c12c4ce31a..78d41a1949651 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -34,6 +34,7 @@ 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)
@@ -188,6 +189,7 @@ 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;

@@ -253,6 +255,9 @@ 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);
@@ -266,6 +271,7 @@ 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);
}
}

@@ -434,8 +440,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
bool huge_page_disallowed = exec && nx_huge_page_workaround_enabled;
struct kvm_mmu *mmu = vcpu->arch.mmu;
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;
@@ -479,7 +484,9 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
}

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);
--
2.28.0.1011.ga647a8990f-goog