| Message ID | 20260330122601.22140-5-fangyu.yu@linux.alibaba.com |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Support runtime configuration for per-VM's HGATP mode | expand |
On Mon, Mar 30, 2026 at 8:26 PM <fangyu.yu@linux.alibaba.com> wrote: > > From: Fangyu Yu <fangyu.yu@linux.alibaba.com> > > Add a VM capability that allows userspace to select the G-stage page table > format by setting HGATP.MODE on a per-VM basis. > > Userspace enables the capability via KVM_ENABLE_CAP, passing the requested > HGATP.MODE in args[0]. The request is rejected with -EINVAL if the mode is > not supported by the host, and with -EBUSY if the VM has already been > committed (e.g. vCPUs have been created or any memslot is populated). > > KVM_CHECK_EXTENSION(KVM_CAP_RISCV_SET_HGATP_MODE) returns a bitmask of the > HGATP.MODE formats supported by the host. > > Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com> > Reviewed-by: Andrew Jones <andrew.jones@oss.qualcomm.com> > --- > Documentation/virt/kvm/api.rst | 27 +++++++++++++++++++++++++++ > arch/riscv/kvm/vm.c | 18 ++++++++++++++++-- > include/uapi/linux/kvm.h | 1 + > 3 files changed, 44 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 032516783e96..9d7f6958fa81 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -8902,6 +8902,33 @@ helpful if user space wants to emulate instructions which are not > This capability can be enabled dynamically even if VCPUs were already > created and are running. > > +7.47 KVM_CAP_RISCV_SET_HGATP_MODE > +--------------------------------- > + > +:Architectures: riscv > +:Type: VM > +:Parameters: args[0] contains the requested HGATP mode > +:Returns: > + - 0 on success. > + - -EINVAL if args[0] is outside the range of HGATP modes supported by the > + hardware. > + - -EBUSY if vCPUs have already been created for the VM, if the VM has any > + non-empty memslots. > + > +This capability allows userspace to explicitly select the HGATP mode for > +the VM. The selected mode must be supported by both KVM and hardware. This > +capability must be enabled before creating any vCPUs or memslots. > + > +If this capability is not enabled, KVM will select the default HGATP mode > +automatically. The default is the highest HGATP.MODE value supported by > +hardware. > + > +``KVM_CHECK_EXTENSION(KVM_CAP_RISCV_SET_HGATP_MODE)`` returns a bitmask of > +HGATP.MODE values supported by the host. A return value of 0 indicates that > +the capability is not supported. Supported-mode bitmask use HGATP.MODE > +encodings as defined by the RISC-V privileged specification, such as Sv39x4 > +corresponds to HGATP.MODE=8, so userspace should test bitmask & BIT(8). > + > 8. Other capabilities. > ====================== > > diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c > index 4d82a886102c..5e82a3ad3ad0 100644 > --- a/arch/riscv/kvm/vm.c > +++ b/arch/riscv/kvm/vm.c > @@ -201,6 +201,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_VM_GPA_BITS: > r = kvm_riscv_gstage_gpa_bits(kvm->arch.pgd_levels); > break; > + case KVM_CAP_RISCV_SET_HGATP_MODE: > + r = kvm_riscv_get_hgatp_mode_mask(); > + break; > default: > r = 0; > break; > @@ -211,12 +214,23 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > > int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) > { > + if (cap->flags) > + return -EINVAL; > + > switch (cap->cap) { > case KVM_CAP_RISCV_MP_STATE_RESET: > - if (cap->flags) > - return -EINVAL; > kvm->arch.mp_state_reset = true; > return 0; > + case KVM_CAP_RISCV_SET_HGATP_MODE: > + if (!kvm_riscv_hgatp_mode_is_valid(cap->args[0])) > + return -EINVAL; > + > + if (kvm->created_vcpus || !kvm_are_all_memslots_empty(kvm)) > + return -EBUSY; > +#ifdef CONFIG_64BIT > + kvm->arch.pgd_levels = 3 + cap->args[0] - HGATP_MODE_SV39X4; > +#endif > + return 0; > default: > return -EINVAL; > } > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 80364d4dbebb..a74a80fd4046 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -989,6 +989,7 @@ struct kvm_enable_cap { > #define KVM_CAP_ARM_SEA_TO_USER 245 > #define KVM_CAP_S390_USER_OPEREXEC 246 > #define KVM_CAP_S390_KEYOP 247 > +#define KVM_CAP_RISCV_SET_HGATP_MODE 248 > > struct kvm_irq_routing_irqchip { > __u32 irqchip; > -- > 2.50.1 > Reviewed-by: Guo Ren <guoren@kernel.org>
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 032516783e96..9d7f6958fa81 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8902,6 +8902,33 @@ helpful if user space wants to emulate instructions which are not This capability can be enabled dynamically even if VCPUs were already created and are running. +7.47 KVM_CAP_RISCV_SET_HGATP_MODE +--------------------------------- + +:Architectures: riscv +:Type: VM +:Parameters: args[0] contains the requested HGATP mode +:Returns: + - 0 on success. + - -EINVAL if args[0] is outside the range of HGATP modes supported by the + hardware. + - -EBUSY if vCPUs have already been created for the VM, if the VM has any + non-empty memslots. + +This capability allows userspace to explicitly select the HGATP mode for +the VM. The selected mode must be supported by both KVM and hardware. This +capability must be enabled before creating any vCPUs or memslots. + +If this capability is not enabled, KVM will select the default HGATP mode +automatically. The default is the highest HGATP.MODE value supported by +hardware. + +``KVM_CHECK_EXTENSION(KVM_CAP_RISCV_SET_HGATP_MODE)`` returns a bitmask of +HGATP.MODE values supported by the host. A return value of 0 indicates that +the capability is not supported. Supported-mode bitmask use HGATP.MODE +encodings as defined by the RISC-V privileged specification, such as Sv39x4 +corresponds to HGATP.MODE=8, so userspace should test bitmask & BIT(8). + 8. Other capabilities. ====================== diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c index 4d82a886102c..5e82a3ad3ad0 100644 --- a/arch/riscv/kvm/vm.c +++ b/arch/riscv/kvm/vm.c @@ -201,6 +201,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_VM_GPA_BITS: r = kvm_riscv_gstage_gpa_bits(kvm->arch.pgd_levels); break; + case KVM_CAP_RISCV_SET_HGATP_MODE: + r = kvm_riscv_get_hgatp_mode_mask(); + break; default: r = 0; break; @@ -211,12 +214,23 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) { + if (cap->flags) + return -EINVAL; + switch (cap->cap) { case KVM_CAP_RISCV_MP_STATE_RESET: - if (cap->flags) - return -EINVAL; kvm->arch.mp_state_reset = true; return 0; + case KVM_CAP_RISCV_SET_HGATP_MODE: + if (!kvm_riscv_hgatp_mode_is_valid(cap->args[0])) + return -EINVAL; + + if (kvm->created_vcpus || !kvm_are_all_memslots_empty(kvm)) + return -EBUSY; +#ifdef CONFIG_64BIT + kvm->arch.pgd_levels = 3 + cap->args[0] - HGATP_MODE_SV39X4; +#endif + return 0; default: return -EINVAL; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 80364d4dbebb..a74a80fd4046 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -989,6 +989,7 @@ struct kvm_enable_cap { #define KVM_CAP_ARM_SEA_TO_USER 245 #define KVM_CAP_S390_USER_OPEREXEC 246 #define KVM_CAP_S390_KEYOP 247 +#define KVM_CAP_RISCV_SET_HGATP_MODE 248 struct kvm_irq_routing_irqchip { __u32 irqchip;