On Thu, Dec 16, 2021 at 12:31:34PM +0000, Marc Zyngier wrote:
> Just as arm64 implemenations don't necessary support all IPA
> ranges, they don't all support the same page sizes either. Fun.
>
> Create a dummy VM to snapshot the page sizes supported by the
> host, and filter the supported modes.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/lib/guest_modes.c | 51 ++++++++++++++++---
> 1 file changed, 45 insertions(+), 6 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/guest_modes.c b/tools/testing/selftests/kvm/lib/guest_modes.c
> index fadc99bac69c..8db9ea2c4032 100644
> --- a/tools/testing/selftests/kvm/lib/guest_modes.c
> +++ b/tools/testing/selftests/kvm/lib/guest_modes.c
> @@ -5,7 +5,42 @@
> #include "guest_modes.h"
>
> #ifdef __aarch64__
> +#include "processor.h"
> enum vm_guest_mode vm_mode_default;
> +static void get_supported_psz(uint32_t ipa,
> + bool *ps4k, bool *ps16k, bool *ps64k)
> +{
> + struct kvm_vcpu_init preferred_init;
> + int kvm_fd, vm_fd, vcpu_fd, err;
> + uint64_t val;
> + struct kvm_one_reg reg = {
> + .id = KVM_ARM64_SYS_REG(SYS_ID_AA64MMFR0_EL1),
> + .addr = (uint64_t)&val,
> + };
> +
> + kvm_fd = open_kvm_dev_path_or_exit();
> + vm_fd = ioctl(kvm_fd, KVM_CREATE_VM, ipa);
> + TEST_ASSERT(vm_fd >= 0, "Can't create VM");
> +
> + vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, 0);
> + TEST_ASSERT(vcpu_fd >= 0, "Can't create vcpu");
> +
> + err = ioctl(vm_fd, KVM_ARM_PREFERRED_TARGET, &preferred_init);
> + TEST_ASSERT(err == 0, "Can't get target");
> + err = ioctl(vcpu_fd, KVM_ARM_VCPU_INIT, &preferred_init);
> + TEST_ASSERT(err == 0, "Can't get init vcpu");
> +
> + err = ioctl(vcpu_fd, KVM_GET_ONE_REG, ®);
> + TEST_ASSERT(err == 0, "Can't get MMFR0");
> +
> + *ps4k = ((val >> 28) & 0xf) != 0xf;
> + *ps64k = ((val >> 24) & 0xf) == 0;
> + *ps16k = ((val >> 20) & 0xf) != 0;
> +
> + close(vcpu_fd);
> + close(vm_fd);
> + close(kvm_fd);
> +}
I think I'd prefer stashing this function in lib/aarch64/processor.c and
naming it aarch64_get_supported_page_sizes.
> #endif
>
> struct guest_mode guest_modes[NUM_VM_MODES];
> @@ -18,20 +53,24 @@ void guest_modes_append_default(void)
> #ifdef __aarch64__
> {
> unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
> + bool ps4k, ps16k, ps64k;
> int i;
>
> + get_supported_psz(limit, &ps4k, &ps16k, &ps64k);
> +
> vm_mode_default = NUM_VM_MODES;
>
> if (limit >= 52)
> - guest_mode_append(VM_MODE_P52V48_64K, true, true);
> + guest_mode_append(VM_MODE_P52V48_64K, ps64k, ps64k);
> if (limit >= 48) {
> - guest_mode_append(VM_MODE_P48V48_4K, true, true);
> - guest_mode_append(VM_MODE_P48V48_64K, true, true);
> + guest_mode_append(VM_MODE_P48V48_4K, ps4k, ps4k);
> + guest_mode_append(VM_MODE_P48V48_64K, ps64k, ps64k);
> }
> if (limit >= 40) {
> - guest_mode_append(VM_MODE_P40V48_4K, true, true);
> - guest_mode_append(VM_MODE_P40V48_64K, true, true);
> - vm_mode_default = VM_MODE_P40V48_4K;
> + guest_mode_append(VM_MODE_P40V48_4K, ps4k, ps4k);
> + guest_mode_append(VM_MODE_P40V48_64K, ps64k, ps64k);
> + if (ps4k)
> + vm_mode_default = VM_MODE_P40V48_4K;
> }
>
> /* Pick the largest supported IPA size */
> --
> 2.30.2
>
Thanks,
drew
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