linux-kernel - [RFC PATCH 09/16] KVM: arm64: Track perm fault granule in "struct kvm_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250821210042.3451147-10-seanjc@google.com>
Date: Thu, 21 Aug 2025 14:00:35 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, Sean Christopherson <seanjc@...gle.com>, 
	James Houghton <jthoughton@...gle.com>
Subject: [RFC PATCH 09/16] KVM: arm64: Track perm fault granule in "struct kvm_page_fault"

Add permission fault granule information to "struct kvm_page_fault", to
help capture that the granule is a property of the fault, and to make the
information readily available, e.g. without needing to be explicitly
passed if it's needed by a helper.

Opportunistically drop kvm_vcpu_trap_get_perm_fault_granule() and simply
grab the granule from the passed-in ESR.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/arm64/include/asm/kvm_emulate.h |  9 ---------
 arch/arm64/include/asm/kvm_host.h    |  1 +
 arch/arm64/kvm/mmu.c                 | 13 ++++++-------
 3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 8065f54927cb..93e7a0bad0fb 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -449,15 +449,6 @@ bool kvm_vcpu_trap_is_translation_fault(const struct kvm_vcpu *vcpu)
 	return esr_fsc_is_translation_fault(kvm_vcpu_get_esr(vcpu));
 }
 
-static inline
-u64 kvm_vcpu_trap_get_perm_fault_granule(const struct kvm_vcpu *vcpu)
-{
-	unsigned long esr = kvm_vcpu_get_esr(vcpu);
-
-	BUG_ON(!esr_fsc_is_permission_fault(esr));
-	return esr_fsc_perm_fault_granule(esr);
-}
-
 static __always_inline bool kvm_vcpu_abt_issea(const struct kvm_vcpu *vcpu)
 {
 	switch (kvm_vcpu_trap_get_fault(vcpu)) {
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 4623cbc1edf4..ec6473007fb9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -418,6 +418,7 @@ struct kvm_page_fault {
 	const bool exec;
 	const bool write;
 	const bool is_perm;
+	const u64  granule;
 
 	phys_addr_t fault_ipa; /* The address we faulted on */
 	phys_addr_t ipa; /* Always the IPA in the L1 guest phys space */
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index c6aadd8baa18..10c73494d505 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1483,14 +1483,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	short vma_shift;
 	void *memcache;
 	bool logging_active = memslot_is_logging(fault->slot);
-	long vma_pagesize, fault_granule;
+	long vma_pagesize;
 	enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
 	struct kvm_pgtable *pgt;
 	vm_flags_t vm_flags;
 	enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED;
 
-	if (fault->is_perm)
-		fault_granule = kvm_vcpu_trap_get_perm_fault_granule(vcpu);
 	VM_BUG_ON(fault->write && fault->exec);
 
 	if (fault->is_perm && !fault->write && !fault->exec) {
@@ -1715,8 +1713,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	 * backed by a THP and thus use block mapping if possible.
 	 */
 	if (vma_pagesize == PAGE_SIZE && !(force_pte || s2_force_noncacheable)) {
-		if (fault->is_perm && fault_granule > PAGE_SIZE)
-			vma_pagesize = fault_granule;
+		if (fault->is_perm && fault->granule > PAGE_SIZE)
+			vma_pagesize = fault->granule;
 		else
 			vma_pagesize = transparent_hugepage_adjust(kvm, fault);
 
@@ -1754,10 +1752,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 
 	/*
 	 * Under the premise of getting a FSC_PERM fault, we just need to relax
-	 * permissions only if vma_pagesize equals fault_granule. Otherwise,
+	 * permissions only if vma_pagesize equals fault->granule. Otherwise,
 	 * kvm_pgtable_stage2_map() should be called to change block size.
 	 */
-	if (fault->is_perm && vma_pagesize == fault_granule) {
+	if (fault->is_perm && vma_pagesize == fault->granule) {
 		/*
 		 * Drop the SW bits in favour of those stored in the
 		 * PTE, which will be preserved.
@@ -1806,6 +1804,7 @@ static int __kvm_handle_guest_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa
 		.write = kvm_is_write_fault(vcpu),
 		.exec  = kvm_vcpu_trap_is_exec_fault(vcpu),
 		.is_perm = esr_fsc_is_permission_fault(esr),
+		.granule = esr_fsc_is_permission_fault(esr) ? esr_fsc_perm_fault_granule(esr) : 0,
 	};
 	struct kvm_s2_trans nested_trans;
 	bool writable;
-- 
2.51.0.261.g7ce5a0a67e-goog