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KVM: Use enum to track if cached PFN will be used in guest and/or host

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Replace the guest_uses_pa and kernel_map booleans in the PFN cache code
with a unified enum/bitmask. Using explicit names makes it easier to
review and audit call sites.

Opportunistically add a WARN to prevent passing garbage; instantating a
cache without declaring its usage is either buggy or pointless.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-03-03 15:41:11 +00:00 committed by Paolo Bonzini
parent 4a9e7b9ea2
commit d0d96121d0
4 changed files with 24 additions and 18 deletions
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2
arch/x86/kvm/xen.c
View File

@ -39,7 +39,7 @@ static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
}
do {
ret = kvm_gfn_to_pfn_cache_init(kvm, gpc, NULL, false, true,
ret = kvm_gfn_to_pfn_cache_init(kvm, gpc, NULL, KVM_HOST_USES_PFN,
gpa, PAGE_SIZE, false);
if (ret)
goto out;

16
include/linux/kvm_host.h
View File

@ -1231,11 +1231,12 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn);
* @gpc: struct gfn_to_pfn_cache object.
* @vcpu: vCPU to be used for marking pages dirty and to be woken on
* invalidation.
* @guest_uses_pa: indicates that the resulting host physical PFN is used while
* @vcpu is IN_GUEST_MODE; invalidations of the cache from MMU
* notifiers (but not for KVM memslot changes!) will also force
* @vcpu to exit the guest to refresh the cache.
* @kernel_map: requests a kernel virtual mapping (kmap / memremap).
* @usage: indicates if the resulting host physical PFN is used while
* the @vcpu is IN_GUEST_MODE (in which case invalidation of
* the cache from MMU notifiers---but not for KVM memslot
* changes!---will also force @vcpu to exit the guest and
* refresh the cache); and/or if the PFN used directly
* by KVM (and thus needs a kernel virtual mapping).
* @gpa: guest physical address to map.
* @len: sanity check; the range being access must fit a single page.
* @dirty: mark the cache dirty immediately.
@ -1250,9 +1251,8 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn);
* accessing the target page.
*/
int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
struct kvm_vcpu *vcpu, bool guest_uses_pa,
bool kernel_map, gpa_t gpa, unsigned long len,
bool dirty);
struct kvm_vcpu *vcpu, enum pfn_cache_usage usage,
gpa_t gpa, unsigned long len, bool dirty);
/**
* kvm_gfn_to_pfn_cache_check - check validity of a gfn_to_pfn_cache.

10
include/linux/kvm_types.h
View File

@ -18,6 +18,7 @@ struct kvm_memslots;
enum kvm_mr_change;
#include <linux/bits.h>
#include <linux/types.h>
#include <linux/spinlock_types.h>
@ -46,6 +47,12 @@ typedef u64 hfn_t;
typedef hfn_t kvm_pfn_t;
enum pfn_cache_usage {
KVM_GUEST_USES_PFN = BIT(0),
KVM_HOST_USES_PFN = BIT(1),
KVM_GUEST_AND_HOST_USE_PFN = KVM_GUEST_USES_PFN | KVM_HOST_USES_PFN,
};
struct gfn_to_hva_cache {
u64 generation;
gpa_t gpa;
@ -64,11 +71,10 @@ struct gfn_to_pfn_cache {
rwlock_t lock;
void *khva;
kvm_pfn_t pfn;
enum pfn_cache_usage usage;
bool active;
bool valid;
bool dirty;
bool kernel_map;
bool guest_uses_pa;
};
#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE

14
virt/kvm/pfncache.c
View File

@ -42,7 +42,7 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
* If a guest vCPU could be using the physical address,
* it needs to be forced out of guest mode.
*/
if (gpc->guest_uses_pa) {
if (gpc->usage & KVM_GUEST_USES_PFN) {
if (!evict_vcpus) {
evict_vcpus = true;
bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS);
@ -224,7 +224,7 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
goto map_done;
}
if (gpc->kernel_map) {
if (gpc->usage & KVM_HOST_USES_PFN) {
if (new_pfn == old_pfn) {
new_khva = old_khva;
old_pfn = KVM_PFN_ERR_FAULT;
@ -304,10 +304,11 @@ EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_unmap);
int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
struct kvm_vcpu *vcpu, bool guest_uses_pa,
bool kernel_map, gpa_t gpa, unsigned long len,
bool dirty)
struct kvm_vcpu *vcpu, enum pfn_cache_usage usage,
gpa_t gpa, unsigned long len, bool dirty)
{
WARN_ON_ONCE(!usage || (usage & KVM_GUEST_AND_HOST_USE_PFN) != usage);
if (!gpc->active) {
rwlock_init(&gpc->lock);
@ -315,8 +316,7 @@ int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
gpc->pfn = KVM_PFN_ERR_FAULT;
gpc->uhva = KVM_HVA_ERR_BAD;
gpc->vcpu = vcpu;
gpc->kernel_map = kernel_map;
gpc->guest_uses_pa = guest_uses_pa;
gpc->usage = usage;
gpc->valid = false;
gpc->active = true;