[PATCH 2/4] KVM: arm64: Match hyp text by physical address in fix_host_ownership()

[Fuad Tabba]

On a non-hVHE host, fix_host_ownership_walker()'s test for PAGE_HYP_EXEC
never matches: KVM_PGTABLE_PROT_UX is cleared at map time and only PX is
reported on read-back. Hyp text is therefore donated rather than left
read-only in the host stage-2, and the instruction dump in
nvhe_hyp_panic_handler() reads a page the host has no access to.

Match the text by physical address instead, in a helper a later patch
reuses. A test on the permissions would leave any other executable
mapping host-readable too.

Fixes: 80cbfd7174f31 ("KVM: arm64: Honor UX/PX attributes for EL2 S1 mappings")
Signed-off-by: Fuad Tabba <fuad.tabba at linux.dev>
---
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 8 ++++++++
 arch/arm64/kvm/hyp/nvhe/setup.c               | 2 +-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 29935c7da1dec..cab27f7bd423a 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -52,6 +52,7 @@ int __pkvm_host_test_clear_young_guest(u64 gfn, u64 nr_pages, bool mkold, struct
 int __pkvm_host_mkyoung_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu);
 
 bool addr_is_memory(phys_addr_t phys);
+bool addr_is_hyp_text(phys_addr_t phys);
 int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);
 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id);
 int kvm_host_prepare_stage2(void *pgt_pool_base);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 39aa8911f62c1..d026f446bd8ef 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -450,6 +450,14 @@ bool addr_is_memory(phys_addr_t phys)
 	return !!find_mem_range(phys, &range);
 }
 
+bool addr_is_hyp_text(phys_addr_t phys)
+{
+	phys_addr_t start = ALIGN_DOWN(__hyp_pa(__hyp_text_start), PAGE_SIZE);
+	phys_addr_t end = PAGE_ALIGN(__hyp_pa(__hyp_text_end));
+
+	return phys >= start && phys < end;
+}
+
 static bool is_in_mem_range(u64 addr, struct kvm_mem_range *range)
 {
 	return range->start <= addr && addr < range->end;
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 362f2891cb32e..bb667cd7080b4 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -217,7 +217,7 @@ static int fix_host_ownership_walker(const struct kvm_pgtable_visit_ctx *ctx,
 	case PKVM_PAGE_OWNED:
 		set_hyp_state(page, PKVM_PAGE_OWNED);
 		/* hyp text is RO in the host stage-2 to be inspected on panic. */
-		if (prot == PAGE_HYP_EXEC) {
+		if (addr_is_hyp_text(phys)) {
 			set_host_state(page, PKVM_NOPAGE);
 			return host_stage2_idmap_locked(phys, PAGE_SIZE, KVM_PGTABLE_PROT_R);
 		} else {
-- 
2.39.5