[PATCH v2 17/21] KVM: arm64: Use common code's approach for __GFP_ZERO with memory caches

Sean Christopherson
2020-06-22T20:09:44Z

Add a "gfp_zero" member to arm64's 'struct kvm_mmu_memory_cache' to make
the struct and its usage compatible with the common 'struct
kvm_mmu_memory_cache' in linux/kvm_host.h. This will minimize code
churn when arm64 moves to the common implementation in a future patch, at
the cost of temporarily having somewhat silly code.

Note, GFP_PGTABLE_USER is equivalent to GFP_KERNEL_ACCOUNT | GFP_ZERO:

#define GFP_PGTABLE_USER (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
|
-> #define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO)

== GFP_KERNEL | __GFP_ACCOUNT | __GFP_ZERO

versus

#define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)

with __GFP_ZERO explicitly OR'd in

== GFP_KERNEL | __GFP_ACCOUNT | __GFP_ZERO

No functional change intended.

Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/kvm/arm.c | 2 ++
arch/arm64/kvm/mmu.c | 5 +++--
3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index c3e6fcc664b1..335170b59899 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -105,6 +105,7 @@ struct kvm_arch {
*/
struct kvm_mmu_memory_cache {
int nobjs;
+ gfp_t gfp_zero;
void *objects[KVM_NR_MEM_OBJS];
};

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 90cb90561446..1016635b3782 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -270,6 +270,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.target = -1;
bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);

+ vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
+
/* Set up the timer */
kvm_timer_vcpu_init(vcpu);

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 9398b66f8a87..688213ef34f0 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -131,7 +131,8 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, int min)
if (cache->nobjs >= min)
return 0;
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
- page = (void *)__get_free_page(GFP_PGTABLE_USER);
+ page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT |
+ cache->gfp_zero);
if (!page)
return -ENOMEM;
cache->objects[cache->nobjs++] = page;
@@ -1342,7 +1343,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
phys_addr_t addr, end;
int ret = 0;
unsigned long pfn;
- struct kvm_mmu_memory_cache cache = { 0, };
+ struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, };

end = (guest_ipa + size + PAGE_SIZE - 1) & PAGE_MASK;
pfn = __phys_to_pfn(pa);
--
2.26.0