[PATCH] KVM: arm64: Remove redundant check for S2FWB

[Jing Zhang]

Remove redundant check for CPU feature S2FWB in dcache flush code
to save some CPU cycles for every memslot flush and unmapping.
And move the S2FWB check to outer functions to avoid future
redundancy and keep consistent with other usage like in
access_dcsw and kvm_arch_prepare_memory_region.

Signed-off-by: Jing Zhang <jingzhangos at google.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 9 ++-------
 arch/arm64/kvm/mmu.c         | 3 ++-
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index bdf8e55ed308..afd57564b1cb 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -642,9 +642,6 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 
 static void stage2_flush_dcache(void *addr, u64 size)
 {
-	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
-		return;
-
 	__flush_dcache_area(addr, size);
 }
 
@@ -670,7 +667,8 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 
 		if (page_count(virt_to_page(childp)) != 1)
 			return 0;
-	} else if (stage2_pte_cacheable(pte)) {
+	} else if (stage2_pte_cacheable(pte) &&
+			!cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) {
 		need_flush = true;
 	}
 
@@ -846,9 +844,6 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
 		.flags	= KVM_PGTABLE_WALK_LEAF,
 	};
 
-	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
-		return 0;
-
 	return kvm_pgtable_walk(pgt, addr, size, &walker);
 }
 
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 7d2257cc5438..53130ed23304 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1458,7 +1458,8 @@ void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled)
 	 * If switching it off, need to clean the caches.
 	 * Clean + invalidate does the trick always.
 	 */
-	if (now_enabled != was_enabled)
+	if (now_enabled != was_enabled &&
+			!cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
 		stage2_flush_vm(vcpu->kvm);
 
 	/* Caches are now on, stop trapping VM ops (until a S/W op) */

base-commit: a8ac864a7d6dbc2fc43081b1eecd9e0183065d47
-- 
2.30.0.365.g02bc693789-goog