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From: Fuad Tabba <tabba@google.com>
To: kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
	kvmarm@lists.linux.dev,  linux-arm-kernel@lists.infradead.org
Cc: maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com,
	 suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org,
	 pbonzini@redhat.com, shuah@kernel.org, anup@brainfault.org,
	 itaru.kitayama@fujitsu.com, andrew.jones@linux.dev,
	tabba@google.com
Subject: [PATCH v3 2/5] KVM: arm64: selftests: Fix incorrect rounding in page_align()
Date: Tue,  6 Jan 2026 09:24:22 +0000	[thread overview]
Message-ID: <20260106092425.1529428-3-tabba@google.com> (raw)
In-Reply-To: <20260106092425.1529428-1-tabba@google.com>

The implementation of `page_align()` in `processor.c` calculates
alignment incorrectly for values that are already aligned. Specifically,
`(v + vm->page_size) & ~(vm->page_size - 1)` aligns to the *next* page
boundary even if `v` is already page-aligned, potentially wasting a page
of memory.

Fix the calculation to use standard alignment logic: `(v + vm->page_size
- 1) & ~(vm->page_size - 1)`.

Fixes: 7a6629ef746d ("kvm: selftests: add virt mem support for aarch64")
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 tools/testing/selftests/kvm/lib/arm64/processor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/arm64/processor.c b/tools/testing/selftests/kvm/lib/arm64/processor.c
index 5b379da8cb90..607a4e462984 100644
--- a/tools/testing/selftests/kvm/lib/arm64/processor.c
+++ b/tools/testing/selftests/kvm/lib/arm64/processor.c
@@ -23,7 +23,7 @@ static vm_vaddr_t exception_handlers;
 
 static uint64_t page_align(struct kvm_vm *vm, uint64_t v)
 {
-	return (v + vm->page_size) & ~(vm->page_size - 1);
+	return (v + vm->page_size - 1) & ~(vm->page_size - 1);
 }
 
 static uint64_t pgd_index(struct kvm_vm *vm, vm_vaddr_t gva)
-- 
2.52.0.351.gbe84eed79e-goog


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WARNING: multiple messages have this Message-ID (diff)
From: Fuad Tabba <tabba@google.com>
To: kvm@vger.kernel.org, kvm-riscv@lists.infradead.org,
	kvmarm@lists.linux.dev,  linux-arm-kernel@lists.infradead.org
Cc: maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com,
	 suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org,
	 pbonzini@redhat.com, shuah@kernel.org, anup@brainfault.org,
	 itaru.kitayama@fujitsu.com, andrew.jones@linux.dev,
	tabba@google.com
Subject: [PATCH v3 2/5] KVM: arm64: selftests: Fix incorrect rounding in page_align()
Date: Tue,  6 Jan 2026 09:24:22 +0000	[thread overview]
Message-ID: <20260106092425.1529428-3-tabba@google.com> (raw)
In-Reply-To: <20260106092425.1529428-1-tabba@google.com>

The implementation of `page_align()` in `processor.c` calculates
alignment incorrectly for values that are already aligned. Specifically,
`(v + vm->page_size) & ~(vm->page_size - 1)` aligns to the *next* page
boundary even if `v` is already page-aligned, potentially wasting a page
of memory.

Fix the calculation to use standard alignment logic: `(v + vm->page_size
- 1) & ~(vm->page_size - 1)`.

Fixes: 7a6629ef746d ("kvm: selftests: add virt mem support for aarch64")
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 tools/testing/selftests/kvm/lib/arm64/processor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/arm64/processor.c b/tools/testing/selftests/kvm/lib/arm64/processor.c
index 5b379da8cb90..607a4e462984 100644
--- a/tools/testing/selftests/kvm/lib/arm64/processor.c
+++ b/tools/testing/selftests/kvm/lib/arm64/processor.c
@@ -23,7 +23,7 @@ static vm_vaddr_t exception_handlers;
 
 static uint64_t page_align(struct kvm_vm *vm, uint64_t v)
 {
-	return (v + vm->page_size) & ~(vm->page_size - 1);
+	return (v + vm->page_size - 1) & ~(vm->page_size - 1);
 }
 
 static uint64_t pgd_index(struct kvm_vm *vm, vm_vaddr_t gva)
-- 
2.52.0.351.gbe84eed79e-goog


  parent reply	other threads:[~2026-01-06  9:24 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-06  9:24 [PATCH v3 0/5] KVM: selftests: Alignment fixes and arm64 MMU cleanup Fuad Tabba
2026-01-06  9:24 ` Fuad Tabba
2026-01-06  9:24 ` [PATCH v3 1/5] KVM: arm64: selftests: Disable unused TTBR1_EL1 translations Fuad Tabba
2026-01-06  9:24   ` Fuad Tabba
2026-01-06  9:24 ` Fuad Tabba [this message]
2026-01-06  9:24   ` [PATCH v3 2/5] KVM: arm64: selftests: Fix incorrect rounding in page_align() Fuad Tabba
2026-01-06  9:24 ` [PATCH v3 3/5] KVM: riscv: " Fuad Tabba
2026-01-06  9:24   ` Fuad Tabba
2026-01-06  9:24 ` [PATCH v3 4/5] KVM: selftests: Move page_align() to shared header Fuad Tabba
2026-01-06  9:24   ` Fuad Tabba
2026-01-06 19:46   ` Sean Christopherson
2026-01-06 19:46     ` Sean Christopherson
2026-01-06 19:48     ` Fuad Tabba
2026-01-06 19:48       ` Fuad Tabba
2026-01-06  9:24 ` [PATCH v3 5/5] KVM: selftests: Fix typos and stale comments in kvm_util Fuad Tabba
2026-01-06  9:24   ` Fuad Tabba

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