[PATCH v2 08/22] KVM: arm64: Add a range to hyp_poison_page()

[Vincent Donnefort]

In preparation for supporting stage-2 huge mappings for protected VMs,
add a nr_pages argument to the memory poisoning mechanism. Use the
existing __apply_guest_page() helper which speeds up the process by
using a PMD_SIZE fixmap when possible.

Also, rename the function to hyp_poison_range() to reflect the new
capability.

Signed-off-by: Vincent Donnefort <vdonnefort at google.com>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 58ea0fa62226..642096b2e711 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1276,11 +1276,9 @@ static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *s
 	return 0;
 }
 
-static void hyp_poison_page(phys_addr_t phys)
+static void __hyp_poison_page(void *addr, size_t size)
 {
-	void *addr = hyp_fixmap_map(phys);
-
-	memset(addr, 0, PAGE_SIZE);
+	memset(addr, 0, size);
 	/*
 	 * Prefer kvm_flush_dcache_to_poc() over __clean_dcache_guest_page()
 	 * here as the latter may elide the CMO under the assumption that FWB
@@ -1288,8 +1286,12 @@ static void hyp_poison_page(phys_addr_t phys)
 	 * host stage-2 and would otherwise lead to a malicious host potentially
 	 * being able to read the contents of newly reclaimed guest pages.
 	 */
-	kvm_flush_dcache_to_poc(addr, PAGE_SIZE);
-	hyp_fixmap_unmap();
+	kvm_flush_dcache_to_poc(addr, size);
+}
+
+static void hyp_poison_range(phys_addr_t phys, u64 size)
+{
+	__apply_guest_page(__hyp_va(phys), size, __hyp_poison_page);
 }
 
 static int host_stage2_get_guest_info(phys_addr_t phys, struct pkvm_hyp_vm **vm,
@@ -1361,7 +1363,7 @@ int __pkvm_host_force_reclaim_page_guest(phys_addr_t phys)
 	if (ret)
 		goto unlock_guest;
 
-	hyp_poison_page(phys);
+	hyp_poison_range(phys, PAGE_SIZE);
 	WARN_ON(host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_HOST));
 unlock_guest:
 	guest_unlock_component(vm);
@@ -1389,7 +1391,7 @@ int __pkvm_host_reclaim_page_guest(u64 gfn, struct pkvm_hyp_vm *vm)
 	switch (guest_get_page_state(pte, ipa)) {
 	case PKVM_PAGE_OWNED:
 		WARN_ON(__host_check_page_state_range(phys, PAGE_SIZE, PKVM_NOPAGE));
-		hyp_poison_page(phys);
+		hyp_poison_range(phys, PAGE_SIZE);
 		break;
 	case PKVM_PAGE_SHARED_OWNED:
 		WARN_ON(__host_check_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_BORROWED));
-- 
2.55.0.1007.g17ff1f9808-goog