[Patch v2 2/2] KVM: x86/mmu: Allocate page table pages on NUMA node of underlying pages

Vipin Sharma
2022-12-01T19:58:32Z

Page table pages of a VM are currently allocated based on the current
task's NUMA node or its mempolicy. This can cause suboptimal remote
accesses by the vCPU if it is accessing physical pages local to its NUMA
node but the page table pages mapping those physcal pages were created
by some other vCPU which was on different NUMA node or had different
policy.

Allocate page table pages on the same NUMA node where underlying
physical page exists. Page table at level 5, 4, and 3 might not end up
on the same NUMA node as they can span multiple NUMA nodes.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
arch/x86/include/asm/kvm_host.h | 4 +-
arch/x86/kvm/mmu.h | 1 -
arch/x86/kvm/mmu/mmu.c | 109 ++++++++++++++++++++++----------
arch/x86/kvm/mmu/paging_tmpl.h | 4 +-
arch/x86/kvm/mmu/tdp_mmu.c | 16 +++--
include/linux/kvm_host.h | 2 +
include/linux/kvm_types.h | 2 +
virt/kvm/kvm_main.c | 7 +-
8 files changed, 101 insertions(+), 44 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 283cbb83d6ae..8a0293326abc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -782,7 +782,7 @@ struct kvm_vcpu_arch {
struct kvm_mmu *walk_mmu;

struct kvm_mmu_memory_cache mmu_pte_list_desc_cache;
- struct kvm_mmu_memory_cache mmu_shadow_page_cache;
+ struct kvm_mmu_memory_cache mmu_shadow_page_cache[MAX_NUMNODES];
struct kvm_mmu_memory_cache mmu_shadowed_info_cache;
struct kvm_mmu_memory_cache mmu_page_header_cache;

@@ -1415,7 +1415,7 @@ struct kvm_arch {
*
* Protected by kvm->slots_lock.
*/
- struct kvm_mmu_memory_cache split_shadow_page_cache;
+ struct kvm_mmu_memory_cache split_shadow_page_cache[MAX_NUMNODES];
struct kvm_mmu_memory_cache split_page_header_cache;

/*
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index c960fb096e5c..6bdaacb6faa0 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -119,7 +119,6 @@ void kvm_mmu_unload(struct kvm_vcpu *vcpu);
void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu);
void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu);
void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu);
-void *kvm_mmu_get_free_page(int nid, gfp_t gfp);

static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
{
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0554dfc55553..ff7b17af8ab8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -648,31 +648,43 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)

static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
{
- int r;
+ int r, i;

/* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */
r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM);
if (r)
return r;
- r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache,
- PT64_ROOT_MAX_LEVEL);
- if (r)
- return r;
+
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ if (node_online(i)) {
+ r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache[i],
+ PT64_ROOT_MAX_LEVEL);
+ if (r)
+ return r;
+ }
+ }
+
if (maybe_indirect) {
r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadowed_info_cache,
PT64_ROOT_MAX_LEVEL);
if (r)
return r;
}
+
return kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
PT64_ROOT_MAX_LEVEL);
}

static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
+ int i;
+
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache);
- kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache);
+
+ for (i = 0; i < MAX_NUMNODES; i++)
+ kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache[i]);
+
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadowed_info_cache);
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
}
@@ -2203,13 +2215,17 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm,

static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
gfn_t gfn,
- union kvm_mmu_page_role role)
+ union kvm_mmu_page_role role,
+ int nid)
{
- struct shadow_page_caches caches = {
- .page_header_cache = &vcpu->arch.mmu_page_header_cache,
- .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache,
- .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache,
- };
+ struct shadow_page_caches caches;
+
+ if (nid == NUMA_NO_NODE)
+ nid = numa_mem_id();
+
+ caches.page_header_cache = &vcpu->arch.mmu_page_header_cache;
+ caches.shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache[nid];
+ caches.shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache;

return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role);
}
@@ -2262,15 +2278,19 @@ static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct,

static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu,
u64 *sptep, gfn_t gfn,
- bool direct, unsigned int access)
+ bool direct, unsigned int access,
+ kvm_pfn_t pfn)
{
union kvm_mmu_page_role role;
+ int nid;

if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep))
return ERR_PTR(-EEXIST);

role = kvm_mmu_child_role(sptep, direct, access);
- return kvm_mmu_get_shadow_page(vcpu, gfn, role);
+ nid = kvm_pfn_to_refcounted_page_nid(pfn);
+
+ return kvm_mmu_get_shadow_page(vcpu, gfn, role, nid);
}

static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator,
@@ -3153,7 +3173,8 @@ static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
if (it.level == fault->goal_level)
break;

- sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true,
+ ACC_ALL, fault->pfn);
if (sp == ERR_PTR(-EEXIST))
continue;

@@ -3579,7 +3600,7 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte);
WARN_ON_ONCE(role.direct && role.has_4_byte_gpte);

- sp = kvm_mmu_get_shadow_page(vcpu, gfn, role);
+ sp = kvm_mmu_get_shadow_page(vcpu, gfn, role, NUMA_NO_NODE);
++sp->root_count;

return __pa(sp->spt);
@@ -5853,15 +5874,20 @@ static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)

int kvm_mmu_create(struct kvm_vcpu *vcpu)
{
- int ret;
+ int ret, i;

vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_pte_list_desc_cache.node = NUMA_NO_NODE;

vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_page_header_cache.node = NUMA_NO_NODE;

- vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ vcpu->arch.mmu_shadow_page_cache[i].gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_shadow_page_cache[i].node = i;
+ }

vcpu->arch.mmu = &vcpu->arch.root_mmu;
vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;
@@ -6012,7 +6038,7 @@ static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
int kvm_mmu_init_vm(struct kvm *kvm)
{
struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker;
- int r;
+ int r, i;

INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);
@@ -6029,20 +6055,29 @@ int kvm_mmu_init_vm(struct kvm *kvm)

kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache;
kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO;
+ kvm->arch.split_page_header_cache.node = NUMA_NO_NODE;
+
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ kvm->arch.split_shadow_page_cache[i].gfp_zero = __GFP_ZERO;
+ kvm->arch.split_shadow_page_cache[i].node = i;
+ }

- kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO;

kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache;
kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO;
+ kvm->arch.split_desc_cache.node = NUMA_NO_NODE;

return 0;
}

static void mmu_free_vm_memory_caches(struct kvm *kvm)
{
+ int i;
+
kvm_mmu_free_memory_cache(&kvm->arch.split_desc_cache);
kvm_mmu_free_memory_cache(&kvm->arch.split_page_header_cache);
- kvm_mmu_free_memory_cache(&kvm->arch.split_shadow_page_cache);
+ for (i = 0; i < MAX_NUMNODES; i++)
+ kvm_mmu_free_memory_cache(&kvm->arch.split_shadow_page_cache[i]);
}

void kvm_mmu_uninit_vm(struct kvm *kvm)
@@ -6150,7 +6185,7 @@ static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min)
return kvm_mmu_memory_cache_nr_free_objects(cache) < min;
}

-static bool need_topup_split_caches_or_resched(struct kvm *kvm)
+static bool need_topup_split_caches_or_resched(struct kvm *kvm, int nid)
{
if (need_resched() || rwlock_needbreak(&kvm->mmu_lock))
return true;
@@ -6162,10 +6197,10 @@ static bool need_topup_split_caches_or_resched(struct kvm *kvm)
*/
return need_topup(&kvm->arch.split_desc_cache, SPLIT_DESC_CACHE_MIN_NR_OBJECTS) ||
need_topup(&kvm->arch.split_page_header_cache, 1) ||
- need_topup(&kvm->arch.split_shadow_page_cache, 1);
+ need_topup(&kvm->arch.split_shadow_page_cache[nid], 1);
}

-static int topup_split_caches(struct kvm *kvm)
+static int topup_split_caches(struct kvm *kvm, int nid)
{
/*
* Allocating rmap list entries when splitting huge pages for nested
@@ -6195,16 +6230,19 @@ static int topup_split_caches(struct kvm *kvm)
if (r)
return r;

- return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache, 1);
+ return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache[nid], 1);
}

-static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep)
+static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm,
+ u64 *huge_sptep,
+ u64 huge_spte)
{
struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep);
struct shadow_page_caches caches = {};
union kvm_mmu_page_role role;
unsigned int access;
gfn_t gfn;
+ int nid;

gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep));
access = kvm_mmu_page_get_access(huge_sp, spte_index(huge_sptep));
@@ -6217,9 +6255,13 @@ static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *hu
*/
role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access);

+ nid = kvm_pfn_to_refcounted_page_nid(spte_to_pfn(huge_spte));
+ if (nid == NUMA_NO_NODE)
+ nid = numa_mem_id();
+
/* Direct SPs do not require a shadowed_info_cache. */
caches.page_header_cache = &kvm->arch.split_page_header_cache;
- caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache;
+ caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache[nid];

/* Safe to pass NULL for vCPU since requesting a direct SP. */
return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role);
@@ -6238,7 +6280,7 @@ static void shadow_mmu_split_huge_page(struct kvm *kvm,
gfn_t gfn;
int index;

- sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep);
+ sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep, huge_spte);

for (index = 0; index < SPTE_ENT_PER_PAGE; index++) {
sptep = &sp->spt[index];
@@ -6276,7 +6318,7 @@ static int shadow_mmu_try_split_huge_page(struct kvm *kvm,
u64 *huge_sptep)
{
struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep);
- int level, r = 0;
+ int level, r = 0, nid;
gfn_t gfn;
u64 spte;

@@ -6284,13 +6326,16 @@ static int shadow_mmu_try_split_huge_page(struct kvm *kvm,
gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep));
level = huge_sp->role.level;
spte = *huge_sptep;
+ nid = kvm_pfn_to_refcounted_page_nid(spte_to_pfn(spte));
+ if (nid == NUMA_NO_NODE)
+ nid = numa_mem_id();

if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) {
r = -ENOSPC;
goto out;
}

- if (need_topup_split_caches_or_resched(kvm)) {
+ if (need_topup_split_caches_or_resched(kvm, nid)) {
write_unlock(&kvm->mmu_lock);
cond_resched();
/*
@@ -6298,7 +6343,7 @@ static int shadow_mmu_try_split_huge_page(struct kvm *kvm,
* rmap iterator should be restarted because the MMU lock was
* dropped.
*/
- r = topup_split_caches(kvm) ?: -EAGAIN;
+ r = topup_split_caches(kvm, nid) ?: -EAGAIN;
write_lock(&kvm->mmu_lock);
goto out;
}
@@ -6988,7 +7033,7 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm)
kthread_stop(kvm->arch.nx_huge_page_recovery_thread);
}

-void *kvm_mmu_get_free_page(int nid, gfp_t gfp)
+void *kvm_arch_mmu_get_free_page(int nid, gfp_t gfp)
{
struct page *spt_page;
void *address = NULL;
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 0f6455072055..1b1039a1b178 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -652,7 +652,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
table_gfn = gw->table_gfn[it.level - 2];
access = gw->pt_access[it.level - 2];
sp = kvm_mmu_get_child_sp(vcpu, it.sptep, table_gfn,
- false, access);
+ false, access, fault->pfn);

if (sp != ERR_PTR(-EEXIST)) {
/*
@@ -708,7 +708,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
validate_direct_spte(vcpu, it.sptep, direct_access);

sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn,
- true, direct_access);
+ true, direct_access, fault->pfn);
if (sp == ERR_PTR(-EEXIST))
continue;

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 1607afbfcc0b..be0763e6b058 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -270,12 +270,15 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm,
kvm_mmu_page_as_id(_root) != _as_id) { \
} else

-static struct kvm_mmu_page *tdp_mmu_alloc_sp(struct kvm_vcpu *vcpu)
+static struct kvm_mmu_page *tdp_mmu_alloc_sp(struct kvm_vcpu *vcpu, int nid)
{
struct kvm_mmu_page *sp;

+ if (nid == NUMA_NO_NODE)
+ nid = numa_mem_id();
+
sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+ sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache[nid]);

return sp;
}
@@ -327,7 +330,7 @@ hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu)
goto out;
}

- root = tdp_mmu_alloc_sp(vcpu);
+ root = tdp_mmu_alloc_sp(vcpu, NUMA_NO_NODE);
tdp_mmu_init_sp(root, NULL, 0, role);

refcount_set(&root->tdp_mmu_root_count, 1);
@@ -1159,7 +1162,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
struct kvm *kvm = vcpu->kvm;
struct tdp_iter iter;
struct kvm_mmu_page *sp;
- int ret = RET_PF_RETRY;
+ int ret = RET_PF_RETRY, nid;

kvm_mmu_hugepage_adjust(vcpu, fault);

@@ -1188,11 +1191,12 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
!is_large_pte(iter.old_spte))
continue;

+ nid = kvm_pfn_to_refcounted_page_nid(fault->pfn);
/*
* The SPTE is either non-present or points to a huge page that
* needs to be split.
*/
- sp = tdp_mmu_alloc_sp(vcpu);
+ sp = tdp_mmu_alloc_sp(vcpu, nid);
tdp_mmu_init_child_sp(sp, &iter);

sp->nx_huge_page_disallowed = fault->huge_page_disallowed;
@@ -1423,7 +1427,7 @@ static struct kvm_mmu_page *__tdp_mmu_alloc_sp_for_split(int nid, gfp_t gfp)
if (!sp)
return NULL;

- sp->spt = kvm_mmu_get_free_page(nid, gfp);
+ sp->spt = kvm_arch_mmu_get_free_page(nid, gfp);

if (!sp->spt) {
kmem_cache_free(mmu_page_header_cache, sp);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 558ded73f660..07674955460b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1374,6 +1374,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu, bool usermode_vcpu_not_eligible);

void kvm_flush_remote_tlbs(struct kvm *kvm);

+void *kvm_arch_mmu_get_free_page(int nid, gfp_t gfp);
+
#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity, int min);
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 3ca3db020e0e..cb627cf1b4e1 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -96,6 +96,8 @@ struct kvm_mmu_memory_cache {
struct kmem_cache *kmem_cache;
int capacity;
void **objects;
+ /* Node on which memory should be allocated by default */
+ int node;
};
#endif

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1782c4555d94..4d59c9d48277 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -384,6 +384,11 @@ static void kvm_flush_shadow_all(struct kvm *kvm)
kvm_arch_guest_memory_reclaimed(kvm);
}

+void * __weak kvm_arch_mmu_get_free_page(int nid, gfp_t gfp_flags)
+{
+ return (void *)__get_free_page(gfp_flags);
+}
+
#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
gfp_t gfp_flags)
@@ -393,7 +398,7 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
if (mc->kmem_cache)
return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
else
- return (void *)__get_free_page(gfp_flags);
+ return kvm_arch_mmu_get_free_page(mc->node, gfp_flags);
}

int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity, int min)
--
2.39.0.rc0.267.gcb52ba06e7-goog