2019-05-20 18:03:07

by Paolo Bonzini

Subject: [PATCH] kvm: selftests: avoid type punning

Avoid warnings from -Wstrict-aliasing by using memcpy.

Signed-off-by: Paolo Bonzini <[email protected]>
---
tools/testing/selftests/kvm/lib/ucall.c | 2 +-
tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/ucall.c b/tools/testing/selftests/kvm/lib/ucall.c
index a2ab38be2f47..b701a01cfcb6 100644
--- a/tools/testing/selftests/kvm/lib/ucall.c
+++ b/tools/testing/selftests/kvm/lib/ucall.c
@@ -142,7 +142,7 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
vm_vaddr_t gva;
TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8,
"Unexpected ucall exit mmio address access");
- gva = *(vm_vaddr_t *)run->mmio.data;
+ memcpy(&gva, run->mmio.data, sizeof(gva));
memcpy(uc, addr_gva2hva(vm, gva), sizeof(*uc));
}

diff --git a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
index 61a2163cf9f1..9d62e2c7e024 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
@@ -75,7 +75,7 @@ void set_revision_id_for_vmcs12(struct kvm_nested_state *state,
u32 vmcs12_revision)
{
/* Set revision_id in vmcs12 to vmcs12_revision. */
- *(u32 *)(state->data) = vmcs12_revision;
+ memcpy(state->data, &vmcs12_revision, sizeof(u32));
}

void set_default_state(struct kvm_nested_state *state)
--
1.8.3.1

2019-05-20 18:05:00

by Thomas Huth

Subject: Re: [PATCH] kvm: selftests: avoid type punning

On 20/05/2019 15.38, Paolo Bonzini wrote:
> Avoid warnings from -Wstrict-aliasing by using memcpy.
>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> tools/testing/selftests/kvm/lib/ucall.c | 2 +-
> tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/ucall.c b/tools/testing/selftests/kvm/lib/ucall.c
> index a2ab38be2f47..b701a01cfcb6 100644
> --- a/tools/testing/selftests/kvm/lib/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/ucall.c
> @@ -142,7 +142,7 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
> vm_vaddr_t gva;
> TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8,
> "Unexpected ucall exit mmio address access");
> - gva = *(vm_vaddr_t *)run->mmio.data;
> + memcpy(&gva, run->mmio.data, sizeof(gva));
> memcpy(uc, addr_gva2hva(vm, gva), sizeof(*uc));
> }
>
> diff --git a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
> index 61a2163cf9f1..9d62e2c7e024 100644
> --- a/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/vmx_set_nested_state_test.c
> @@ -75,7 +75,7 @@ void set_revision_id_for_vmcs12(struct kvm_nested_state *state,
> u32 vmcs12_revision)
> {
> /* Set revision_id in vmcs12 to vmcs12_revision. */
> - *(u32 *)(state->data) = vmcs12_revision;
> + memcpy(state->data, &vmcs12_revision, sizeof(u32));
> }
>
> void set_default_state(struct kvm_nested_state *state)
>

Reviewed-by: Thomas Huth <[email protected]>