Messages in this thread |  | | From | Anup Patel <> | | Date | Sat, 4 Apr 2026 16:32:32 +0530 | | Subject | Re: [PATCH v8 0/3] Support runtime configuration for per-VM's HGATP mode |
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On Fri, Apr 3, 2026 at 9:00 PM <fangyu.yu@linux.alibaba.com> wrote: > > From: Fangyu Yu <fangyu.yu@linux.alibaba.com> > > Currently, RISC-V KVM hardcodes the G-stage page table format (HGATP mode) > to the maximum mode detected at boot time (e.g., SV57x4 if supported). but > often such a wide GPA is unnecessary, just as a host sometimes doesn't need > sv57. > > This patch reuse KVM_CAP_VM_GPA_BITS to select HGATP.MODE. User-space can > now explicitly request a specific HGATP mode (SV39x4, SV48x4, SV57x4 or > SV32x4) during VM creation. > > --- > Changes in v8: > - Reuse KVM_CAP_VM_GPA_BITS to advertise and select the effective GPA width > for a VM (Anup's suggestion). > - Handle the kvm == NULL case and task kvm->lock and kvm->slots_lock to serialize > against concurrent vCPU creation and memslot updates (Radim's suggestion). > - Link to v7: > https://lore.kernel.org/linux-riscv/20260402132303.6252-1-fangyu.yu@linux.alibaba.com/ > --- > Changes in v7 (Anup's suggestions): > - Keep the original HGATP mode probing logic. > - Link to v6: > https://lore.kernel.org/linux-riscv/20260330122601.22140-1-fangyu.yu@linux.alibaba.com/ > --- > Changes in v6 (Anup's suggestions): > - Reworked kvm_riscv_gstage_gpa_bits() and kvm_riscv_gstage_gpa_size() to > take "unsigned long pgd_levels" instead of "struct kvm_arch *". > - Moved kvm_riscv_gstage_mode() helper from kvm_host.h to kvm_gstage.h. > - Renamed kvm->arch.kvm_riscv_gstage_pgd_levels to kvm->arch.pgd_levels. > - Added pgd_levels to struct kvm_gstage to avoid repeated > gstage->kvm->arch pointer chasing. > - Link to v5: > https://lore.kernel.org/linux-riscv/20260204134507.33912-1-fangyu.yu@linux.alibaba.com/ > --- > Changes in v5: > - Use architectural HGATP.MODE encodings as the bit index for the supported-mode > bitmap and for the VM-mode selection UAPI; no new UAPI mode/bit defines are > introduced(per Radim). > - Allow KVM_CAP_RISCV_SET_HGATP_MODE on RV32 as well(per Drew). > - Link to v4: > https://lore.kernel.org/linux-riscv/20260202140716.34323-1-fangyu.yu@linux.alibaba.com/ > --- > Changes in v4: > - Extend kvm_riscv_gstage_mode_detect() to probe all HGATP.MODE values > supported by the host and record them in a bitmask. > - Treat unexpected pgd_levels in kvm_riscv_gstage_mode() as an internal error > (e.g. WARN_ON_ONCE())(per Radim). > - Move kvm_riscv_gstage_gpa_bits() and kvm_riscv_gstage_gpa_size() to header > as static inline helpers(per Radim). > - Drop gstage_mode_user_initialized and Remove the kvm_debug() message from > KVM_CAP_RISCV_SET_HGATP_MODE(per Radim). > - Link to v3: > https://lore.kernel.org/linux-riscv/20260125150450.27068-1-fangyu.yu@linux.alibaba.com/ > --- > Changes in v3: > - Reworked the patch formatting (per Drew). > - Dropped kvm->arch.kvm_riscv_gstage_mode and derive HGATP.MODE from > kvm_riscv_gstage_pgd_levels via a helper, avoiding redundant per-VM state(per Drew). > - Removed kvm_riscv_gstage_max_mode and keep only kvm_riscv_gstage_max_pgd_levels > for host capability detection(per Drew). > - Other initialization and return value issues(per Drew). > - Enforce that KVM_CAP_RISCV_SET_HGATP_MODE can only be enabled before any vCPUs > are created by rejecting the ioctl once kvm->created_vcpus is non-zero(per Radim). > - Add a memslot safety check and reject the capability unless > kvm_are_all_memslots_empty(kvm) is true, ensuring the G-stage format is not > changed after any memslots have been installed(per Radim). > - Link to v2: > https://lore.kernel.org/linux-riscv/20260105143232.76715-1-fangyu.yu@linux.alibaba.com/ > > Fangyu Yu (3): > RISC-V: KVM: Support runtime configuration for per-VM's HGATP mode > RISC-V: KVM: Cache gstage pgd_levels in struct kvm_gstage > RISC-V: KVM: Reuse KVM_CAP_VM_GPA_BITS to select HGATP.MODE > > arch/riscv/include/asm/kvm_gstage.h | 47 ++++++++++++++++--- > arch/riscv/include/asm/kvm_host.h | 1 + > arch/riscv/kvm/gstage.c | 65 +++++++++++++-------------- > arch/riscv/kvm/main.c | 12 ++--- > arch/riscv/kvm/mmu.c | 70 +++++++++-------------------- > arch/riscv/kvm/vm.c | 49 ++++++++++++++++++-- > arch/riscv/kvm/vmid.c | 3 +- > 7 files changed, 148 insertions(+), 99 deletions(-) > > -- > 2.50.1 >
Queued this series for Linux-7.1
Thanks, Anup
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