From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: nsaenz@amazon.com, vkuznets@redhat.com, snambakam@linux.microsoft.com
Subject: [PATCH 20/31] KVM: Introduce kvm_check_gen()/kvm_memslots_check_gen()
Date: Fri, 18 Sep 2026 09:50:19 -0400 [thread overview]
Message-ID: <20260918135030.171564-21-pbonzini@redhat.com> (raw)
In-Reply-To: <20260918135030.171564-1-pbonzini@redhat.com>
In many cases, retrieving kvm_memslots is followed by a check on
the generation of the slots. Introduce a helper function that
either does the check alone, or compounds it with returning the
struct kvm_memslots* to the caller.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/loongarch/kvm/vcpu.c | 12 ++++--------
arch/x86/kvm/x86.c | 10 ++--------
include/linux/kvm_host.h | 13 +++++++++++++
virt/kvm/kvm_main.c | 8 ++++----
virt/kvm/pfncache.c | 10 ++++------
5 files changed, 27 insertions(+), 26 deletions(-)
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index d540004d74ff..cf4f4d75374a 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -154,7 +154,6 @@ static void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
u32 version;
u64 steal;
gpa_t gpa;
- struct kvm_memslots *slots;
struct kvm_steal_time __user *st;
struct gfn_to_hva_cache *ghc;
@@ -164,9 +163,8 @@ static void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
return;
gpa &= KVM_STEAL_PHYS_MASK;
- slots = kvm_memslots(vcpu->kvm);
- if (unlikely(slots->generation != ghc->generation || gpa != ghc->gpa ||
- kvm_is_error_hva(ghc->hva) || !ghc->memslot)) {
+ if (unlikely(!kvm_check_gen(vcpu->kvm, ghc->generation) || gpa != ghc->gpa ||
+ kvm_is_error_hva(ghc->hva) || !ghc->memslot) {
if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st))) {
ghc->gpa = INVALID_GPA;
return;
@@ -1794,7 +1792,6 @@ static void kvm_vcpu_set_pv_preempted(struct kvm_vcpu *vcpu)
{
gpa_t gpa;
struct gfn_to_hva_cache *ghc;
- struct kvm_memslots *slots;
struct kvm_steal_time __user *st;
gpa = vcpu->arch.st.guest_addr;
@@ -1811,9 +1808,8 @@ static void kvm_vcpu_set_pv_preempted(struct kvm_vcpu *vcpu)
gpa &= KVM_STEAL_PHYS_MASK;
ghc = &vcpu->arch.st.cache;
- slots = kvm_memslots(vcpu->kvm);
- if (unlikely(slots->generation != ghc->generation || gpa != ghc->gpa ||
- kvm_is_error_hva(ghc->hva) || !ghc->memslot)) {
+ if (unlikely(!kvm_check_gen(vcpu->kvm, ghc->generation) || gpa != ghc->gpa ||
+ kvm_is_error_hva(ghc->hva) || !ghc->memslot) {
if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st))) {
ghc->gpa = INVALID_GPA;
return;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e07966b9ef85..7a1e80bb28f5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2049,7 +2049,6 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
{
struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache;
struct kvm_steal_time __user *st;
- struct kvm_memslots *slots;
gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS;
u64 steal;
u32 version;
@@ -2065,9 +2064,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
if (WARN_ON_ONCE(current->mm != vcpu->kvm->mm))
return;
- slots = kvm_memslots(vcpu->kvm);
-
- if (unlikely(slots->generation != ghc->generation ||
+ if (unlikely(!kvm_check_gen(vcpu->kvm, ghc->generation) ||
gpa != ghc->gpa ||
kvm_is_error_hva(ghc->hva) || !ghc->memslot)) {
/* We rely on the fact that it fits in a single page. */
@@ -2617,7 +2614,6 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
{
struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache;
struct kvm_steal_time __user *st;
- struct kvm_memslots *slots;
static const u8 preempted = KVM_VCPU_PREEMPTED;
gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS;
@@ -2644,9 +2640,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
if (unlikely(current->mm != vcpu->kvm->mm))
return;
- slots = kvm_memslots(vcpu->kvm);
-
- if (unlikely(slots->generation != ghc->generation ||
+ if (unlikely(!kvm_check_gen(vcpu->kvm, ghc->generation) ||
gpa != ghc->gpa ||
kvm_is_error_hva(ghc->hva) || !ghc->memslot))
return;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 24d04322d89e..7599ab7ad7ef 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2644,6 +2644,19 @@ static inline int kvm_mem_attributes_may_write_gfn(struct kvm *kvm, gfn_t gfn)
return kvm_mem_attributes_may_write(attrs);
}
+static inline bool kvm_memslots_check_gen(struct kvm *kvm, u64 slots_generation, struct kvm_memslots **p_slots)
+{
+ struct kvm_memslots *slots = *p_slots = kvm_memslots(kvm);
+ return slots->generation == slots_generation;
+}
+
+static inline bool kvm_check_gen(struct kvm *kvm, u64 slots_generation)
+{
+ struct kvm_memslots *slots;
+ return kvm_memslots_check_gen(kvm, slots_generation, &slots);
+}
+
+
#ifdef CONFIG_KVM_GUEST_MEMFD
int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
gfn_t gfn, kvm_pfn_t *pfn, struct page **page,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b8e419fb6cbf..ea4e9425a82d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3526,14 +3526,14 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
void *data, unsigned int offset,
unsigned long len)
{
- struct kvm_memslots *slots = kvm_memslots(kvm);
+ struct kvm_memslots *slots;
int r;
gpa_t gpa = ghc->gpa + offset;
if (WARN_ON_ONCE(len + offset > ghc->len))
return -EINVAL;
- if (slots->generation != ghc->generation) {
+ if (unlikely(!kvm_memslots_check_gen(kvm, ghc->generation, &slots))) {
if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
return -EFAULT;
}
@@ -3564,14 +3564,14 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
void *data, unsigned int offset,
unsigned long len)
{
- struct kvm_memslots *slots = kvm_memslots(kvm);
+ struct kvm_memslots *slots;
int r;
gpa_t gpa = ghc->gpa + offset;
if (WARN_ON_ONCE(len + offset > ghc->len))
return -EINVAL;
- if (slots->generation != ghc->generation) {
+ if (unlikely(!kvm_memslots_check_gen(kvm, ghc->generation, &slots))) {
if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
return -EFAULT;
}
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 728d2c1b488a..e09703d249bb 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -72,8 +72,6 @@ static bool kvm_gpc_is_valid_len(gpa_t gpa, unsigned long uhva,
bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
{
- struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
-
if (!gpc->active)
return false;
@@ -81,7 +79,7 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
* If the page was cached from a memslot, make sure the memslots have
* not been re-configured.
*/
- if (!kvm_is_error_gpa(gpc->gpa) && gpc->generation != slots->generation)
+ if (!kvm_is_error_gpa(gpc->gpa) && !kvm_check_gen(gpc->kvm, gpc->generation))
return false;
if (kvm_is_error_hva(gpc->uhva))
@@ -290,12 +288,12 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned l
if (gpc->uhva != old_uhva)
hva_change = true;
} else {
- struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
+ struct kvm_memslots *slots;
page_offset = offset_in_page(gpa);
- if (gpc->gpa != gpa || gpc->generation != slots->generation ||
- kvm_is_error_hva(gpc->uhva)) {
+ if (!kvm_memslots_check_gen(gpc->kvm, gpc->generation, &slots) ||
+ gpc->gpa != gpa || kvm_is_error_hva(gpc->uhva)) {
gfn_t gfn = gpa_to_gfn(gpa);
gpc->gpa = gpa;
--
2.52.0
next prev parent reply other threads:[~2026-09-18 13:50 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 13:49 [PATCH v3 00/28] KVM: x86: Introduce memory protection attributes Paolo Bonzini
2026-09-18 13:50 ` [PATCH 01/31] KVM: x86/hyperv: do not overwrite hc->ingpa for slow SIGNAL_EVENT hypercall Paolo Bonzini
2026-09-18 13:50 ` [PATCH 02/31] KVM: selftests: Take into account mixed memory fault flags Paolo Bonzini
2026-09-18 13:50 ` [PATCH 03/31] KVM: Define and communicate KVM_EXIT_MEMORY_FAULT RWX flags to userspace Paolo Bonzini
2026-09-18 13:50 ` [PATCH 04/31] KVM: selftests: Test address translation for Hyper-V direct L2 hypercalls Paolo Bonzini
2026-09-18 13:50 ` [PATCH 05/31] KVM: apply nGPA->GPA translation to KVM_HC_CLOCK_PAIRING Paolo Bonzini
2026-09-18 13:50 ` [PATCH 06/31] KVM: x86: Introduce memory fault on invalid hypercalls reads/writes Paolo Bonzini
2026-09-21 16:56 ` Vitaly Kuznetsov
2026-09-18 13:50 ` [PATCH 07/31] KVM: selftests: test hypercall memory fault exits Paolo Bonzini
2026-09-18 13:50 ` [PATCH 08/31] KVM: x86/mmu: intersect writability from __kvm_faultin_pfn with fault->map_writable Paolo Bonzini
2026-09-18 13:50 ` [PATCH 09/31] KVM: x86/mmu: Extend map_writable to a full ACC_* mask Paolo Bonzini
2026-09-18 13:50 ` [PATCH 10/31] KVM: x86/mmu: Init memslot hugepage information for non-private_mem VMs too Paolo Bonzini
2026-09-18 13:50 ` [PATCH 11/31] KVM: pass kvm == NULL case to kvm_arch_has_private_mem Paolo Bonzini
2026-09-18 13:50 ` [PATCH 12/31] KVM: adjust for presence of more than one attribute Paolo Bonzini
2026-09-18 13:50 ` [PATCH 13/31] KVM: Introduce NR/NW/NX memory attributes Paolo Bonzini
2026-09-18 13:50 ` [PATCH 14/31] KVM: Include memory protections in result of gfn->hva conversion Paolo Bonzini
2026-09-18 13:50 ` [PATCH 15/31] KVM: Introduce kvm_fetch_guest_page() and use it for x86 Paolo Bonzini
2026-09-18 13:50 ` [PATCH 16/31] KVM: Take memory protections into account for memory read/write/fetch Paolo Bonzini
2026-09-18 13:50 ` [PATCH 17/31] KVM: Take memory protections into account for __kvm_vcpu_map Paolo Bonzini
2026-09-18 13:50 ` [PATCH 18/31] KVM: Encapsulate memattrs array into anonymous struct Paolo Bonzini
2026-09-18 13:50 ` [PATCH 19/31] KVM: loongarch: do full validity check on the gfn-to-hva cache Paolo Bonzini
2026-09-18 13:50 ` Paolo Bonzini [this message]
2026-09-18 13:50 ` [PATCH 21/31] KVM: Introduce a generation number for memory attributes Paolo Bonzini
2026-09-18 13:50 ` [PATCH 22/31] KVM: Take memory protections into account for accesses with cached gfn->hva Paolo Bonzini
2026-09-18 13:50 ` [PATCH 23/31] KVM: pfncache: Fail to refresh if it contains memory protections Paolo Bonzini
2026-09-18 13:50 ` [PATCH 24/31] KVM: x86/mmu: Do not prefetch sptes on gfns backed by memory attributes Paolo Bonzini
2026-09-18 13:50 ` [PATCH 25/31] KVM: x86/mmu: Take memory protection attributes into account during faults Paolo Bonzini
2026-09-18 13:50 ` [PATCH 26/31] KVM: x86/mmu: Issue memory fault exit if walk failed due to memory attribute Paolo Bonzini
2026-09-18 13:50 ` [PATCH 27/31] KVM: let kvm_arch_post_set_memory_attributes drop mmu_lock Paolo Bonzini
2026-09-18 13:50 ` [PATCH 28/31] KVM: x86/mmu: Obsolete all roots if memattr contains gPTEs Paolo Bonzini
2026-09-18 13:50 ` [PATCH 29/31] KVM: x86: selftests: Introduce memory protection attributes test Paolo Bonzini
2026-09-18 13:50 ` [PATCH 30/31] KVM: x86: selftests: Introduce memory attributes PTE test Paolo Bonzini
2026-09-18 13:50 ` [PATCH 31/31] KVM: x86: selftests: Introduce memory attributes side-channel tests Paolo Bonzini
2026-09-18 15:20 ` [PATCH v3 00/28] KVM: x86: Introduce memory protection attributes Paolo Bonzini
2026-09-21 16:56 ` Vitaly Kuznetsov
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