On Tue, 10 Oct 2023 at 15:25, Cornelia Huck <cohuck@xxxxxxxxxx> wrote:
>
> We can use read_sys_reg64 to get the SVE_VLS register instead of
> calling GET_ONE_REG directly.
>
> Suggested-by: Gavin Shan <gshan@xxxxxxxxxx>
> Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
> ---
> target/arm/kvm64.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
> index 558c0b88dd69..d40c89a84752 100644
> --- a/target/arm/kvm64.c
> +++ b/target/arm/kvm64.c
> @@ -500,10 +500,6 @@ uint32_t kvm_arm_sve_get_vls(CPUState *cs)
> .target = -1,
> .features[0] = (1 << KVM_ARM_VCPU_SVE),
> };
> - struct kvm_one_reg reg = {
> - .id = KVM_REG_ARM64_SVE_VLS,
> - .addr = (uint64_t)&vls[0],
> - };
> int fdarray[3], ret;
>
> probed = true;
> @@ -512,7 +508,7 @@ uint32_t kvm_arm_sve_get_vls(CPUState *cs)
> error_report("failed to create scratch VCPU with SVE enabled");
> abort();
> }
> - ret = ioctl(fdarray[2], KVM_GET_ONE_REG, ®);
> + ret = read_sys_reg64(fdarray[2], &vls[0], KVM_REG_ARM64_SVE_VLS);
> kvm_arm_destroy_scratch_host_vcpu(fdarray);
> if (ret) {
> error_report("failed to get KVM_REG_ARM64_SVE_VLS: %s",
read_sys_reg64() asserts that the register you're trying to
read is 64 bits, but KVM_REG_ARM64_SVE_VLS is not, it's 512 bits:
#define KVM_REG_ARM64_SVE_VLS (KVM_REG_ARM64 | KVM_REG_ARM64_SVE | \
KVM_REG_SIZE_U512 | 0xffff)
So this change would trip the assert on a host where SVE
is supported and enabled.
thanks
-- PMM
