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

From: Haibo Xu
Date: Mon May 15 2023 - 02:21:36 EST

On Thu, May 11, 2023 at 6:44 PM Andrew Jones <ajones@xxxxxxxxxxxxxxxx> wrote:
>
> 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

Thanks for your review, Andrew! The comments will be addressed in next version.