[PATCH 2/2] KVM: riscv: selftests: Detect supported vm modes
Andrew Jones
ajones at ventanamicro.com
Fri Oct 17 09:04:44 PDT 2025
On Fri, Oct 17, 2025 at 11:15:57AM +0800, wu.fei9 at sanechips.com.cn wrote:
> The default vm mode on riscv is hardcoded to sv48, which causes tests to
> fail on platform supporting sv39 only, such as '-cpu rva23s64' on qemu.
> This patch detects the support vm modes and sets default to the maximum
> supported one.
>
> Signed-off-by: Wu Fei <wu.fei9 at sanechips.com.cn>
> ---
> .../testing/selftests/kvm/include/kvm_util.h | 4 ++-
> .../selftests/kvm/include/riscv/processor.h | 2 ++
> tools/testing/selftests/kvm/lib/guest_modes.c | 24 +++++++++----
> .../selftests/kvm/lib/riscv/processor.c | 36 +++++++++++++++++++
> 4 files changed, 59 insertions(+), 7 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 02224bc514d4..7bc2ee9f0cad 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -234,7 +234,9 @@ extern enum vm_guest_mode vm_mode_default;
> #error "RISC-V 32-bit kvm selftests not supported"
> #endif
>
> -#define VM_MODE_DEFAULT VM_MODE_P50V48_4K
> +extern enum vm_guest_mode vm_mode_default;
We can just move this declaration out of the #ifdef __aarch64__ region.
It shouldn't harm other architectures.
> +
> +#define VM_MODE_DEFAULT vm_mode_default
> #define MIN_PAGE_SHIFT 12U
> #define ptes_per_page(page_size) ((page_size) / 8)
>
> diff --git a/tools/testing/selftests/kvm/include/riscv/processor.h b/tools/testing/selftests/kvm/include/riscv/processor.h
> index 162f303d9daa..2d5a5548e698 100644
> --- a/tools/testing/selftests/kvm/include/riscv/processor.h
> +++ b/tools/testing/selftests/kvm/include/riscv/processor.h
> @@ -191,4 +191,6 @@ static inline void local_irq_disable(void)
> csr_clear(CSR_SSTATUS, SR_SIE);
> }
>
> +unsigned long riscv64_get_satp_mode(void);
> +
> #endif /* SELFTEST_KVM_PROCESSOR_H */
> diff --git a/tools/testing/selftests/kvm/lib/guest_modes.c b/tools/testing/selftests/kvm/lib/guest_modes.c
> index 63d0d5479188..9c4a9e86223e 100644
> --- a/tools/testing/selftests/kvm/lib/guest_modes.c
> +++ b/tools/testing/selftests/kvm/lib/guest_modes.c
> @@ -4,7 +4,7 @@
> */
> #include "guest_modes.h"
>
> -#ifdef __aarch64__
> +#if defined(__aarch64__) || defined(__riscv)
> #include "processor.h"
> enum vm_guest_mode vm_mode_default;
> #endif
> @@ -13,9 +13,11 @@ struct guest_mode guest_modes[NUM_VM_MODES];
>
> void guest_modes_append_default(void)
> {
> -#ifndef __aarch64__
> +#if !defined(__aarch64__) && !defined(__riscv)
> guest_mode_append(VM_MODE_DEFAULT, true);
> -#else
> +#endif
> +
> +#ifdef __aarch64__
> {
> unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
> uint32_t ipa4k, ipa16k, ipa64k;
> @@ -74,10 +76,20 @@ void guest_modes_append_default(void)
> #ifdef __riscv
> {
> unsigned int sz = kvm_check_cap(KVM_CAP_VM_GPA_BITS);
> + unsigned long satp_mode = riscv64_get_satp_mode() << SATP_MODE_SHIFT;
> + int i;
>
> - guest_mode_append(VM_MODE_P56V57_4K, sz >= 59);
> - guest_mode_append(VM_MODE_P50V48_4K, sz >= 50);
> - guest_mode_append(VM_MODE_P41V39_4K, sz >= 41);
> + guest_mode_append(VM_MODE_P56V57_4K, satp_mode >= SATP_MODE_57 && sz >= 59);
> + guest_mode_append(VM_MODE_P50V48_4K, satp_mode >= SATP_MODE_48 && sz >= 50);
> + guest_mode_append(VM_MODE_P41V39_4K, satp_mode >= SATP_MODE_39 && sz >= 41);
Something along these lines was what I was suggesting in the last patch,
but where we select from many more combinations of P and V for modes.
VM_MODE_P41V39_4K
VM_MODE_P41V48_4K
VM_MODE_P41V57_4K
VM_MODE_P50V48_4K
VM_MODE_P50V57_4K
VM_MODE_P59V57_4K
> +
> + // set the first (maximum) supported mode as default
Please, no C++ comments, and don't we want a V39 mode to be the default?
In fact, VM_MODE_P41V39_4K should always be supported, so we can just set
VM_MODE_DEFAULT to that.
Thanks,
drew
> + vm_mode_default = NUM_VM_MODES;
> + for (i = 0; vm_mode_default == NUM_VM_MODES && i < NUM_VM_MODES; i++) {
> + if (guest_modes[i].supported && guest_modes[i].enabled)
> + vm_mode_default = i;
> + }
> + TEST_ASSERT(vm_mode_default != NUM_VM_MODES, "No supported mode!");
> }
> #endif
> }
> diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
> index de84c092f982..eac67cb21f50 100644
> --- a/tools/testing/selftests/kvm/lib/riscv/processor.c
> +++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
> @@ -8,6 +8,7 @@
> #include <linux/compiler.h>
> #include <assert.h>
>
> +#include "guest_modes.h"
> #include "kvm_util.h"
> #include "processor.h"
> #include "ucall_common.h"
> @@ -528,3 +529,38 @@ unsigned long get_host_sbi_spec_version(void)
>
> return ret.value;
> }
> +
> +void kvm_selftest_arch_init(void)
> +{
> + /*
> + * riscv64 doesn't have a true default mode, so start by detecting the
> + * supported vm mode.
> + */
> + guest_modes_append_default();
> +}
> +
> +unsigned long riscv64_get_satp_mode(void)
> +{
> + int kvm_fd, vm_fd, vcpu_fd, err;
> + uint64_t val;
> + struct kvm_one_reg reg = {
> + .id = RISCV_CONFIG_REG(satp_mode),
> + .addr = (uint64_t)&val,
> + };
> +
> + kvm_fd = open_kvm_dev_path_or_exit();
> + vm_fd = __kvm_ioctl(kvm_fd, KVM_CREATE_VM, NULL);
> + TEST_ASSERT(vm_fd >= 0, KVM_IOCTL_ERROR(KVM_CREATE_VM, vm_fd));
> +
> + vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, 0);
> + TEST_ASSERT(vcpu_fd >= 0, KVM_IOCTL_ERROR(KVM_CREATE_VCPU, vcpu_fd));
> +
> + err = ioctl(vcpu_fd, KVM_GET_ONE_REG, ®);
> + TEST_ASSERT(err == 0, KVM_IOCTL_ERROR(KVM_GET_ONE_REG, vcpu_fd));
> +
> + close(vcpu_fd);
> + close(vm_fd);
> + close(kvm_fd);
> +
> + return val;
> +}
> --
> 2.43.0
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