linux-kernel - [PATCH v3 1/9] KVM: arm64: Handle huge mappings for np-guest CMOs

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Message-ID: <20250407082706.1239603-2-vdonnefort@google.com>
Date: Mon,  7 Apr 2025 09:26:58 +0100
From: Vincent Donnefort <vdonnefort@...gle.com>
To: maz@...nel.org, oliver.upton@...ux.dev, joey.gouly@....com, 
	suzuki.poulose@....com, yuzenghui@...wei.com, catalin.marinas@....com, 
	will@...nel.org
Cc: qperret@...gle.com, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org, kernel-team@...roid.com, 
	Vincent Donnefort <vdonnefort@...gle.com>
Subject: [PATCH v3 1/9] KVM: arm64: Handle huge mappings for np-guest CMOs

clean_dcache_guest_page() and invalidate_icache_guest_page() accept a
size as an argument. But they also rely on fixmap, which can only map a
single PAGE_SIZE page.

With the upcoming stage-2 huge mappings for pKVM np-guests, those
callbacks will get size > PAGE_SIZE. Loop the CMOs on a PAGE_SIZE basis
until the whole range is done.

Signed-off-by: Vincent Donnefort <vdonnefort@...gle.com>

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index f34f11c720d7..6a90e7687f1f 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -219,14 +219,28 @@ static void guest_s2_put_page(void *addr)
 
 static void clean_dcache_guest_page(void *va, size_t size)
 {
-	__clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size);
-	hyp_fixmap_unmap();
+	WARN_ON(!PAGE_ALIGNED(size));
+
+	while (size) {
+		__clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)),
+					  PAGE_SIZE);
+		hyp_fixmap_unmap();
+		va += PAGE_SIZE;
+		size -= PAGE_SIZE;
+	}
 }
 
 static void invalidate_icache_guest_page(void *va, size_t size)
 {
-	__invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size);
-	hyp_fixmap_unmap();
+	WARN_ON(!PAGE_ALIGNED(size));
+
+	while (size) {
+		__invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)),
+					       PAGE_SIZE);
+		hyp_fixmap_unmap();
+		va += PAGE_SIZE;
+		size -= PAGE_SIZE;
+	}
 }
 
 int kvm_guest_prepare_stage2(struct pkvm_hyp_vm *vm, void *pgd)
-- 
2.49.0.504.g3bcea36a83-goog