On Fri, Apr 22, 2022 at 8:38 PM Atish Patra <atishp@xxxxxxxxxxxx> wrote: > > Currently, there is no provision for vmm (qemu-kvm or kvmtool) to > query about multiple-letter ISA extensions. The config register > is only used for base single letter ISA extensions. > > A new ISA extension register is added that will allow the vmm > to query about any ISA extension one at a time. It is enabled for > both single letter or multi-letter ISA extensions. The ISA extension > register is useful to if the vmm requires to retrieve/set single > extension while the config register should be used if all the base > ISA extension required to retrieve or set. > > For any multi-letter ISA extensions, the new register interface > must be used. > > Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx> > --- > Changes from v1->v2: > 1. Sending the patch separate from sstc series as it is unrelated. > 2. Removed few redundant lines. > > The kvm tool patches can be found here. > > https://github.com/atishp04/kvmtool/tree/sstc_v2 > > --- > arch/riscv/include/uapi/asm/kvm.h | 20 +++++++ > arch/riscv/kvm/vcpu.c | 98 +++++++++++++++++++++++++++++++ > 2 files changed, 118 insertions(+) > > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h > index f808ad1ce500..92bd469e2ba6 100644 > --- a/arch/riscv/include/uapi/asm/kvm.h > +++ b/arch/riscv/include/uapi/asm/kvm.h > @@ -82,6 +82,23 @@ struct kvm_riscv_timer { > __u64 state; > }; > > +/** > + * ISA extension IDs specific to KVM. This is not the same as the host ISA > + * extension IDs as that is internal to the host and should not be exposed > + * to the guest. This should always be contiguous to keep the mapping simple > + * in KVM implementation. > + */ > +enum KVM_RISCV_ISA_EXT_ID { > + KVM_RISCV_ISA_EXT_A = 0, > + KVM_RISCV_ISA_EXT_C, > + KVM_RISCV_ISA_EXT_D, > + KVM_RISCV_ISA_EXT_F, > + KVM_RISCV_ISA_EXT_H, > + KVM_RISCV_ISA_EXT_I, > + KVM_RISCV_ISA_EXT_M, > + KVM_RISCV_ISA_EXT_MAX, > +}; > + > /* Possible states for kvm_riscv_timer */ > #define KVM_RISCV_TIMER_STATE_OFF 0 > #define KVM_RISCV_TIMER_STATE_ON 1 > @@ -123,6 +140,9 @@ struct kvm_riscv_timer { > #define KVM_REG_RISCV_FP_D_REG(name) \ > (offsetof(struct __riscv_d_ext_state, name) / sizeof(__u64)) > > +/* ISA Extension registers are mapped as type 7 */ > +#define KVM_REG_RISCV_ISA_EXT (0x07 << KVM_REG_RISCV_TYPE_SHIFT) > + > #endif > > #endif /* __LINUX_KVM_RISCV_H */ > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index aad430668bb4..93492eb292fd 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -365,6 +365,100 @@ static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu, > return 0; > } > > +/* Mapping between KVM ISA Extension ID & Host ISA extension ID */ > +static unsigned long kvm_isa_ext_arr[] = { > + RISCV_ISA_EXT_a, > + RISCV_ISA_EXT_c, > + RISCV_ISA_EXT_d, > + RISCV_ISA_EXT_f, > + RISCV_ISA_EXT_h, > + RISCV_ISA_EXT_i, > + RISCV_ISA_EXT_m, > +}; > + > +static int kvm_riscv_vcpu_get_reg_isa_ext(struct kvm_vcpu *vcpu, > + const struct kvm_one_reg *reg) > +{ > + unsigned long __user *uaddr = > + (unsigned long __user *)(unsigned long)reg->addr; > + unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK | > + KVM_REG_SIZE_MASK | > + KVM_REG_RISCV_ISA_EXT); > + unsigned long reg_val = 0; > + unsigned long host_isa_ext; > + > + if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long)) > + return -EINVAL; > + > + if (reg_num >= KVM_RISCV_ISA_EXT_MAX || reg_num >= ARRAY_SIZE(kvm_isa_ext_arr)) > + return -EINVAL; > + > + host_isa_ext = kvm_isa_ext_arr[reg_num]; > + if (__riscv_isa_extension_available(NULL, host_isa_ext)) This should be "__riscv_isa_extension_available(vcpu->arch.isa, host_isa_ext)". > + reg_val = 1; /* Mark the given extension as available */ > + > + if (copy_to_user(uaddr, ®_val, KVM_REG_SIZE(reg->id))) > + return -EFAULT; > + > + return 0; > +} > + > +static int kvm_riscv_vcpu_set_reg_isa_ext(struct kvm_vcpu *vcpu, > + const struct kvm_one_reg *reg) > +{ > + unsigned long __user *uaddr = > + (unsigned long __user *)(unsigned long)reg->addr; > + unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK | > + KVM_REG_SIZE_MASK | > + KVM_REG_RISCV_ISA_EXT); > + unsigned long reg_val; > + unsigned long host_isa_ext; > + unsigned long host_isa_ext_mask; > + > + if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long)) > + return -EINVAL; > + > + if (reg_num >= KVM_RISCV_ISA_EXT_MAX || reg_num >= ARRAY_SIZE(kvm_isa_ext_arr)) > + return -EINVAL; > + > + if (copy_from_user(®_val, uaddr, KVM_REG_SIZE(reg->id))) > + return -EFAULT; > + > + host_isa_ext = kvm_isa_ext_arr[reg_num]; > + if (!__riscv_isa_extension_available(NULL, host_isa_ext)) > + return -EOPNOTSUPP; > + > + if (host_isa_ext >= RISCV_ISA_EXT_BASE && > + host_isa_ext < RISCV_ISA_EXT_MAX) { > + /** Multi-letter ISA extension. Currently there is no provision > + * to enable/disable the multi-letter ISA extensions for guests. > + * Return success if the request is to enable any ISA extension > + * that is available in the hardware. > + * Return -EOPNOTSUPP otherwise. > + */ Use double-winged comment-block for multi-line comments. > + if (!reg_val) > + return -EOPNOTSUPP; > + else > + return 0; > + } > + > + /* Single letter base ISA extension */ > + if (!vcpu->arch.ran_atleast_once) { > + host_isa_ext_mask = BIT_MASK(host_isa_ext); > + if (!reg_val && (host_isa_ext_mask & KVM_RISCV_ISA_DISABLE_ALLOWED)) > + vcpu->arch.isa &= ~host_isa_ext_mask; > + else > + vcpu->arch.isa |= host_isa_ext_mask; > + vcpu->arch.isa &= riscv_isa_extension_base(NULL); > + vcpu->arch.isa &= KVM_RISCV_ISA_ALLOWED; > + kvm_riscv_vcpu_fp_reset(vcpu); > + } else { > + return -EOPNOTSUPP; > + } > + > + return 0; > +} > + > static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu, > const struct kvm_one_reg *reg) > { > @@ -382,6 +476,8 @@ static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu, > else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_D) > return kvm_riscv_vcpu_set_reg_fp(vcpu, reg, > KVM_REG_RISCV_FP_D); > + else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_ISA_EXT) > + return kvm_riscv_vcpu_set_reg_isa_ext(vcpu, reg); > > return -EINVAL; > } > @@ -403,6 +499,8 @@ static int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu, > else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_D) > return kvm_riscv_vcpu_get_reg_fp(vcpu, reg, > KVM_REG_RISCV_FP_D); > + else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_ISA_EXT) > + return kvm_riscv_vcpu_get_reg_isa_ext(vcpu, reg); > > return -EINVAL; > } > -- > 2.25.1 > Regards, Anup
