linux-kernel - [PATCH v2 15/16] KVM: arm64: Provide option to pass page walker flag for huge page splits

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Message-ID: <20230602160914.4011728-16-vipinsh@google.com>
Date:   Fri,  2 Jun 2023 09:09:13 -0700
From:   Vipin Sharma <vipinsh@...gle.com>
To:     maz@...nel.org, oliver.upton@...ux.dev, james.morse@....com,
        suzuki.poulose@....com, yuzenghui@...wei.com,
        catalin.marinas@....com, will@...nel.org, chenhuacai@...nel.org,
        aleksandar.qemu.devel@...il.com, tsbogend@...ha.franken.de,
        anup@...infault.org, atishp@...shpatra.org,
        paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, seanjc@...gle.com, pbonzini@...hat.com,
        dmatlack@...gle.com, ricarkol@...gle.com
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-mips@...r.kernel.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-kselftest@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Vipin Sharma <vipinsh@...gle.com>
Subject: [PATCH v2 15/16] KVM: arm64: Provide option to pass page walker flag
 for huge page splits

Pass enum kvm_pgtable_walk_flags{} to kvm_mmu_split_huge_pages().
Use 0 as the flag value to make it no-op.

In future commit kvm_mmu_split_huge_pages() will be used under both MMU
read lock and MMU write lock. Flag allows to pass intent to use shared
or non-shared page walkers to split the huge pages.

Signed-off-by: Vipin Sharma <vipinsh@...gle.com>
---
 arch/arm64/kvm/mmu.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 34d2bd03cf5f..6dd964e3682c 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -118,7 +118,8 @@ static bool need_split_memcache_topup_or_resched(struct kvm *kvm)
 }
 
 static int kvm_mmu_split_huge_pages(struct kvm *kvm, phys_addr_t addr,
-				    phys_addr_t end)
+				    phys_addr_t end,
+				    enum kvm_pgtable_walk_flags flags)
 {
 	struct kvm_mmu_memory_cache *cache;
 	struct kvm_pgtable *pgt;
@@ -153,7 +154,8 @@ static int kvm_mmu_split_huge_pages(struct kvm *kvm, phys_addr_t addr,
 			return -EINVAL;
 
 		next = __stage2_range_addr_end(addr, end, chunk_size);
-		ret = kvm_pgtable_stage2_split(pgt, addr, next - addr, cache, 0);
+		ret = kvm_pgtable_stage2_split(pgt, addr, next - addr, cache,
+					       flags);
 		if (ret)
 			break;
 	} while (addr = next, addr != end);
@@ -1112,7 +1114,7 @@ static void kvm_mmu_split_memory_region(struct kvm *kvm, int slot)
 	end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
 
 	write_lock(&kvm->mmu_lock);
-	kvm_mmu_split_huge_pages(kvm, start, end);
+	kvm_mmu_split_huge_pages(kvm, start, end, 0);
 	write_unlock(&kvm->mmu_lock);
 }
 
@@ -1149,7 +1151,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 	 * again.
 	 */
 	if (kvm_dirty_log_manual_protect_and_init_set(kvm))
-		kvm_mmu_split_huge_pages(kvm, start, end);
+		kvm_mmu_split_huge_pages(kvm, start, end, 0);
 	write_unlock(&kvm->mmu_lock);
 }
 
-- 
2.41.0.rc0.172.g3f132b7071-goog