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(-)
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
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 > This series is in good shape now. I will wait one more day to see if there are any comments and after that I will merge for Linux-7.1 Thanks, Anup
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