Re: [PATCH 1/2] riscv: kvm: Add KVM_GET_REG_LIST API support

From: Andrew Jones
Date: Thu May 11 2023 - 06:45:03 EST

On Thu, May 11, 2023 at 05:22:48PM +0800, Haibo Xu wrote:
> KVM_GET_REG_LIST API will return all registers that are available to
> KVM_GET/SET_ONE_REG APIs. It's very useful to identify some platform
> regression issue during VM migration.
>
> Since this API was already supported on arm64, it'd be straightforward

s/it'd be/it is/

> to enable it on riscv with similar code structure.
>
> Signed-off-by: Haibo Xu <haibo1.xu@xxxxxxxxx>
> ---
> Documentation/virt/kvm/api.rst | 2 +-
> arch/riscv/kvm/vcpu.c | 346 +++++++++++++++++++++++++++++++++
> 2 files changed, 347 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index add067793b90..280e89abd004 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -3499,7 +3499,7 @@ VCPU matching underlying host.
> ---------------------
>
> :Capability: basic
> -:Architectures: arm64, mips
> +:Architectures: arm64, mips, riscv
> :Type: vcpu ioctl
> :Parameters: struct kvm_reg_list (in/out)
> :Returns: 0 on success; -1 on error
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 8bd9f2a8a0b9..fb8834e4fa15 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -657,6 +657,334 @@ static int kvm_riscv_vcpu_set_reg_isa_ext(struct kvm_vcpu *vcpu,
> return 0;
> }
>
> +static inline unsigned long num_config_regs(void)
> +{
> + return sizeof(struct kvm_riscv_config) / sizeof(unsigned long);
> +}
> +
> +static int copy_config_reg_indices(u64 __user *uindices)
> +{
> + unsigned int i;
> + int n = num_config_regs();
> +
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_CONFIG | i;
^ this should be
size-ulong

u64 size = IS_ENABLED(CONFIG_32BIT) ? KVM_REG_SIZE_U32 : KVM_REG_SIZE_U64;
u64 reg = KVM_REG_RISCV | size | KVM_REG_RISCV_CONFIG | i;

> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + return n;
> +}
> +
> +static inline unsigned long num_core_regs(void)
> +{
> + return sizeof(struct kvm_riscv_core) / sizeof(unsigned long);
> +}
> +
> +static int copy_core_reg_indices(u64 __user *uindices)
> +{
> + unsigned int i;
> + int n = num_core_regs();
> +
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_CORE | i;
^ size-ulong

> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + return n;
> +}
> +
> +static inline unsigned long num_csr_regs(void)
> +{
> + unsigned long n = sizeof(struct kvm_riscv_csr) / sizeof(unsigned long);
> +
> + if (kvm_riscv_aia_available())
> + n += sizeof(struct kvm_riscv_aia_csr) / sizeof(unsigned long);
> +
> + return n;
> +}
> +
> +static int copy_csr_reg_indices(u64 __user *uindices)
> +{
> + unsigned int i;
> + int n1 = sizeof(struct kvm_riscv_csr) / sizeof(unsigned long);
> + int n2 = 0;
> +
> + /* copy general csr regs */
> + for (i = 0; i < n1; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_CSR |
^ size-ulong

> + KVM_REG_RISCV_CSR_GENERAL | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + /* copy AIA csr regs */
> + if (kvm_riscv_aia_available()) {
> + n2 = sizeof(struct kvm_riscv_aia_csr) / sizeof(unsigned long);
> +
> + for (i = 0; i < n2; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_CSR |
^ size-ulong

> + KVM_REG_RISCV_CSR_AIA | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> + }
> +
> + return n1 + n2;
> +}
> +
> +static inline unsigned long num_timer_regs(void)
> +{
> + return sizeof(struct kvm_riscv_timer) / sizeof(unsigned long);
> +}
> +
> +static int copy_timer_reg_indices(u64 __user *uindices)
> +{
> + unsigned int i;
> + int n = num_timer_regs();
> +
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_TIMER | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + return n;
> +}
> +
> +static inline unsigned long num_fp_f_regs(const struct kvm_vcpu *vcpu)
> +{
> + const struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
> +
> + if (riscv_isa_extension_available(vcpu->arch.isa, f))
> + return sizeof(cntx->fp.f) / sizeof(u32);
> + else
> + return 0;
> +}
> +
> +static int copy_fp_f_reg_indices(const struct kvm_vcpu *vcpu,
> + u64 __user *uindices)
> +{
> + unsigned int i;
> + int n = num_fp_f_regs(vcpu);
> +
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U32 | KVM_REG_RISCV_FP_F | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + return n;
> +}
> +
> +static inline unsigned long num_fp_d_regs(const struct kvm_vcpu *vcpu)
> +{
> + const struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
> +
> + if (riscv_isa_extension_available(vcpu->arch.isa, d))
> + return sizeof(cntx->fp.d.f) / sizeof(u64) + 1;
> + else
> + return 0;
> +}
> +
> +static int copy_fp_d_reg_indices(const struct kvm_vcpu *vcpu,
> + u64 __user *uindices)
> +{
> + unsigned int i;
> + int n = num_fp_d_regs(vcpu);
> + u64 reg;
> +
> + /* copy fp.d.f indeices */

indices

> + for (i = 0; i < n-1; i++) {
> + reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_FP_D | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + /* copy fp.d.fcsr indeices */

indices

> + reg = KVM_REG_RISCV | KVM_REG_SIZE_U32 | KVM_REG_RISCV_FP_D | i;
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + }
> +
> + return n;
> +}
> +
> +static inline unsigned long num_isa_ext_regs(void)
> +{
> + return KVM_RISCV_ISA_EXT_MAX;
> +}
> +
> +static int copy_isa_ext_reg_indices(u64 __user *uindices)
> +{
> + unsigned int i;
> + int n = num_isa_ext_regs();
> +
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_ISA_EXT | i;
^ size-ulong

> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + return n;
> +}
> +
> +static inline unsigned long num_sbi_ext_regs(void)
> +{
> + /* number of KVM_REG_RISCV_SBI_SINGLE +
> + * 2x(number of KVM_REG_RISCV_SBI_MULTI)
> + */

Please use an opening wing '/*' on comments.

> + return KVM_RISCV_SBI_EXT_MAX + 2*(KVM_REG_RISCV_SBI_MULTI_REG_LAST+1);
> +}
> +
> +static int copy_sbi_ext_reg_indices(u64 __user *uindices)
> +{
> + unsigned int i;
> + int n;
> +
> + /* copy KVM_REG_RISCV_SBI_SINGLE */
> + n = KVM_RISCV_SBI_EXT_MAX;
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_SBI_EXT |
^ size-ulong

> + KVM_REG_RISCV_SBI_SINGLE | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + /* copy KVM_REG_RISCV_SBI_MULTI */
> + n = KVM_REG_RISCV_SBI_MULTI_REG_LAST + 1;
> + for (i = 0; i < n; i++) {
> + u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_SBI_EXT |
^ size-ulong

> + KVM_REG_RISCV_SBI_MULTI_EN | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> +
> + reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 | KVM_REG_RISCV_SBI_EXT |
> + KVM_REG_RISCV_SBI_MULTI_DIS | i;
> +
> + if (uindices) {
> + if (put_user(reg, uindices))
> + return -EFAULT;
> + uindices++;
> + }
> + }
> +
> + return num_sbi_ext_regs();
> +}
> +
> +/**
> + * kvm_riscv_vcpu_num_regs - how many registers do we present via KVM_GET/SET_ONE_REG
> + *
> + * This is for all registers.
> + */
> +static unsigned long kvm_riscv_vcpu_num_regs(struct kvm_vcpu *vcpu)
> +{
> + unsigned long res = 0;
> +
> + res += num_config_regs();
> + res += num_core_regs();
> + res += num_csr_regs();
> + res += num_timer_regs();
> + res += num_fp_f_regs(vcpu);
> + res += num_fp_d_regs(vcpu);
> + res += num_isa_ext_regs();
> + res += num_sbi_ext_regs();
> +
> + return res;
> +}
> +
> +/**
> + * kvm_riscv_vcpu_copy_reg_indices - get indices of all registers.
> + */
> +static int kvm_riscv_vcpu_copy_reg_indices(struct kvm_vcpu *vcpu,
> + u64 __user *uindices)
> +{
> + int ret;
> +
> + ret = copy_config_reg_indices(uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_core_reg_indices(uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_csr_reg_indices(uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_timer_reg_indices(uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_fp_f_reg_indices(vcpu, uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_fp_d_reg_indices(vcpu, uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_isa_ext_reg_indices(uindices);
> + if (ret < 0)
> + return ret;
> + uindices += ret;
> +
> + ret = copy_sbi_ext_reg_indices(uindices);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +
> static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
> const struct kvm_one_reg *reg)
> {
> @@ -758,6 +1086,24 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> r = kvm_riscv_vcpu_get_reg(vcpu, &reg);
> break;
> }
> + case KVM_GET_REG_LIST: {
> + struct kvm_reg_list __user *user_list = argp;
> + struct kvm_reg_list reg_list;
> + unsigned int n;
> +
> + r = -EFAULT;
> + if (copy_from_user(&reg_list, user_list, sizeof(reg_list)))
> + break;
> + n = reg_list.n;
> + reg_list.n = kvm_riscv_vcpu_num_regs(vcpu);
> + if (copy_to_user(user_list, &reg_list, sizeof(reg_list)))
> + break;
> + r = -E2BIG;
> + if (n < reg_list.n)
> + break;
> + r = kvm_riscv_vcpu_copy_reg_indices(vcpu, user_list->reg);
> + break;
> + }
> default:
> break;
> }
> --
> 2.34.1
>

Otherwise,

Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>

Thanks,
drew