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KVM: Allow for different capacities in kvm_mmu_memory_cache structs

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Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
declaration time rather than being fixed for all declarations. This will
be used in a follow-up commit to declare an cache in x86 with a capacity
of 512+ objects without having to increase the capacity of all caches in
KVM.

This change requires each cache now specify its capacity at runtime,
since the cache struct itself no longer has a fixed capacity known at
compile time. To protect against someone accidentally defining a
kvm_mmu_memory_cache struct directly (without the extra storage), this
commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().

In order to support different capacities, this commit changes the
objects pointer array to be dynamically allocated the first time the
cache is topped-up.

While here, opportunistically clean up the stack-allocated
kvm_mmu_memory_cache structs in riscv and arm64 to use designated
initializers.

No functional change intended.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-22-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Matlack 2022-06-22 15:27:08 -04:00 • committed by Paolo Bonzini
parent 0cd8dc7398
commit 837f66c712
5 changed files with 38 additions and 9 deletions
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33
virt/kvm/kvm_main.c
View file

@ -396,14 +396,31 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
return (void *)__get_free_page(gfp_flags);
}
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)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT;
void *obj;
if (mc->nobjs >= min)
return 0;
while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
if (unlikely(!mc->objects)) {
if (WARN_ON_ONCE(!capacity))
return -EIO;
mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
if (!mc->objects)
return -ENOMEM;
mc->capacity = capacity;
}
/* It is illegal to request a different capacity across topups. */
if (WARN_ON_ONCE(mc->capacity != capacity))
return -EIO;
while (mc->nobjs < mc->capacity) {
obj = mmu_memory_cache_alloc_obj(mc, gfp);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
@ -411,6 +428,11 @@ int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
return 0;
}
int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
{
return __kvm_mmu_topup_memory_cache(mc, KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, min);
}
int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc)
{
return mc->nobjs;
@ -424,6 +446,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
else
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
kvfree(mc->objects);
mc->objects = NULL;
mc->capacity = 0;
}
void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)