[PATCH v2 14/22] KVM: arm64: Convert write-protect operation to generic page-table API

From: Will Deacon <will@kernel•org>
To: kvmarm@lists•cs.columbia.edu
Cc: kernel-team@android•com, Suzuki Poulose <suzuki.poulose@arm•com>,
	Marc Zyngier <maz@kernel•org>,
	Quentin Perret <qperret@google•com>,
	James Morse <james.morse@arm•com>,
	Catalin Marinas <catalin.marinas@arm•com>,
	Will Deacon <will@kernel•org>,
	linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 14/22] KVM: arm64: Convert write-protect operation to generic page-table API
Date: Tue, 18 Aug 2020 14:28:10 +0100	[thread overview]
Message-ID: <20200818132818.16065-15-will@kernel.org> (raw)
In-Reply-To: <20200818132818.16065-1-will@kernel.org>

From: Quentin Perret <qperret@google•com>

Convert stage2_wp_range() to call the kvm_pgtable_stage2_wrprotect()
function of the generic page-table code instead of walking the page-table
directly.

Cc: Marc Zyngier <maz@kernel•org>
Signed-off-by: Quentin Perret <qperret@google•com>
Signed-off-by: Will Deacon <will@kernel•org>
---
 arch/arm64/kvm/mmu.c | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 98815f6b8471..60f021430fcc 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -66,6 +66,9 @@ static bool is_iomap(unsigned long flags)
 	ret;								\
 })
 
+#define stage2_apply_range_resched(kvm, addr, end, fn)			\
+	stage2_apply_range(kvm, addr, end, fn, true)
+
 static bool memslot_is_logging(struct kvm_memory_slot *memslot)
 {
 	return memslot->dirty_bitmap && !(memslot->flags & KVM_MEM_READONLY);
@@ -1293,27 +1296,7 @@ static void  stage2_wp_p4ds(struct kvm_s2_mmu *mmu, pgd_t *pgd,
 static void stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
 {
 	struct kvm *kvm = mmu->kvm;
-	pgd_t *pgd;
-	phys_addr_t next;
-
-	pgd = mmu->pgd + stage2_pgd_index(kvm, addr);
-	do {
-		/*
-		 * Release kvm_mmu_lock periodically if the memory region is
-		 * large. Otherwise, we may see kernel panics with
-		 * CONFIG_DETECT_HUNG_TASK, CONFIG_LOCKUP_DETECTOR,
-		 * CONFIG_LOCKDEP. Additionally, holding the lock too long
-		 * will also starve other vCPUs. We have to also make sure
-		 * that the page tables are not freed while we released
-		 * the lock.
-		 */
-		cond_resched_lock(&kvm->mmu_lock);
-		if (!READ_ONCE(mmu->pgd))
-			break;
-		next = stage2_pgd_addr_end(kvm, addr, end);
-		if (stage2_pgd_present(kvm, *pgd))
-			stage2_wp_p4ds(mmu, pgd, addr, next);
-	} while (pgd++, addr = next, addr != end);
+	stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_wrprotect);
 }
 
 /**
-- 
2.28.0.220.ged08abb693-goog


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