Re: [PATCH 18/21] KVM: arm64: Use common KVM implementation of MMU memory caches

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On 2020-06-05 22:38, Sean Christopherson wrote:
Move to the common MMU memory cache implementation now that the common
code and arm64's existing code are semantically compatible.

No functional change intended.

Suggested-by: Christoffer Dall <christoffer.dall@xxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
 arch/arm64/include/asm/kvm_host.h  | 12 -------
 arch/arm64/include/asm/kvm_types.h |  2 ++
 arch/arm64/kvm/mmu.c               | 51 ++++++------------------------
 3 files changed, 12 insertions(+), 53 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h
b/arch/arm64/include/asm/kvm_host.h
index 2385dede96e0..d221b6b129fd 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -97,18 +97,6 @@ struct kvm_arch {
 	bool return_nisv_io_abort_to_user;
 };

-#define KVM_NR_MEM_OBJS     40
-
-/*
- * We don't want allocation failures within the mmu code, so we preallocate
- * enough memory for a single page fault in a cache.
- */
-struct kvm_mmu_memory_cache {
-	int nobjs;
-	gfp_t gfp_zero;
-	void *objects[KVM_NR_MEM_OBJS];
-};
-
 struct kvm_vcpu_fault_info {
 	u32 esr_el2;		/* Hyp Syndrom Register */
 	u64 far_el2;		/* Hyp Fault Address Register */
diff --git a/arch/arm64/include/asm/kvm_types.h
b/arch/arm64/include/asm/kvm_types.h
index d0987007d581..9a126b9e2d7c 100644
--- a/arch/arm64/include/asm/kvm_types.h
+++ b/arch/arm64/include/asm/kvm_types.h
@@ -2,5 +2,7 @@
 #ifndef _ASM_ARM64_KVM_TYPES_H
 #define _ASM_ARM64_KVM_TYPES_H

+#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE 40
+
 #endif /* _ASM_ARM64_KVM_TYPES_H */

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 688213ef34f0..976405e2fbb2 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -124,37 +124,6 @@ static void stage2_dissolve_pud(struct kvm *kvm,
phys_addr_t addr, pud_t *pudp)
 	put_page(virt_to_page(pudp));
 }

-static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, int min)
-{
-	void *page;
-
-	if (cache->nobjs >= min)
-		return 0;
-	while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
-		page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT |
-					       cache->gfp_zero);
-		if (!page)
-			return -ENOMEM;
-		cache->objects[cache->nobjs++] = page;
-	}
-	return 0;
-}
-
-static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
-{
-	while (mc->nobjs)
-		free_page((unsigned long)mc->objects[--mc->nobjs]);
-}
-
-static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
-{
-	void *p;
-
-	BUG_ON(!mc || !mc->nobjs);
-	p = mc->objects[--mc->nobjs];
-	return p;
-}
-
 static void clear_stage2_pgd_entry(struct kvm *kvm, pgd_t *pgd,
phys_addr_t addr)
 {
 	pud_t *pud_table __maybe_unused = stage2_pud_offset(kvm, pgd, 0UL);
@@ -1024,7 +993,7 @@ static pud_t *stage2_get_pud(struct kvm *kvm,
struct kvm_mmu_memory_cache *cache
 	if (stage2_pgd_none(kvm, *pgd)) {
 		if (!cache)
 			return NULL;
-		pud = mmu_memory_cache_alloc(cache);
+		pud = kvm_mmu_memory_cache_alloc(cache);
 		stage2_pgd_populate(kvm, pgd, pud);
 		get_page(virt_to_page(pgd));
 	}

Quick note: this patch (as it is) breaks on arm64 due to Mike Rapoport's
P4D rework. I've fixed it locally in order to test the series.

Thanks,

        M.
--
Jazz is not dead. It just smells funny...



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