| Message ID | 20250215173816.3767330-1-maz@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: arm64: NV userspace ABI | expand |
On Sat, Feb 15, 2025 at 05:38:02PM +0000, Marc Zyngier wrote: > Since the previous incarnation of the ABI was proved to be subtly > wrong, I have reworked it to be more in line with the current way KVM > operates. > > No more late NV-specific adjustment nor writable ID_AA64MMFR0_EL1.VH. > The NV configuration is now entirely selected from the vcpu flags. > I've preserved the KVM_ARM_VCPU_EL2 flag which enables NV with VHE, > and added KVM_ARM_VCPU_EL2_E2H0 which alters the NV behaviour to only > allow nVHE guests without recursive NV support. > > This series is actually very little new code. The bulk of it is > converting the feature downgrade to be per-idreg, essentially going > back to the state before 44241f34fac96 ("KVM: arm64: nv: Use accessors > for modifying ID registers"), only slightly modernised. This then > becomes part of the reset value computing. > > The rest is simply what you'd expect in terms of being able to write > the ID_AA64MMFR4_EL1.NV_frac field, making the correct bits RES0 when > needed, probing for capabilities and handling the init flags. > > Patches on top of -rc2, with the integration branch at the usual > location. This all looks reasonable to me. NV won't be ready for the limelight this time around so unless someone shouts I plan on taking the first 12 patches of this series in 6.15. Thanks, Oliver
On Wed, 19 Feb 2025 23:17:31 +0000, Oliver Upton <oliver.upton@linux.dev> wrote: > > On Sat, Feb 15, 2025 at 05:38:02PM +0000, Marc Zyngier wrote: > > Since the previous incarnation of the ABI was proved to be subtly > > wrong, I have reworked it to be more in line with the current way KVM > > operates. > > > > No more late NV-specific adjustment nor writable ID_AA64MMFR0_EL1.VH. > > The NV configuration is now entirely selected from the vcpu flags. > > I've preserved the KVM_ARM_VCPU_EL2 flag which enables NV with VHE, > > and added KVM_ARM_VCPU_EL2_E2H0 which alters the NV behaviour to only > > allow nVHE guests without recursive NV support. > > > > This series is actually very little new code. The bulk of it is > > converting the feature downgrade to be per-idreg, essentially going > > back to the state before 44241f34fac96 ("KVM: arm64: nv: Use accessors > > for modifying ID registers"), only slightly modernised. This then > > becomes part of the reset value computing. > > > > The rest is simply what you'd expect in terms of being able to write > > the ID_AA64MMFR4_EL1.NV_frac field, making the correct bits RES0 when > > needed, probing for capabilities and handling the init flags. > > > > Patches on top of -rc2, with the integration branch at the usual > > location. > > This all looks reasonable to me. NV won't be ready for the limelight > this time around so unless someone shouts I plan on taking the first 12 > patches of this series in 6.15. Let me repost it first, as I fixed an embarrassing bug that led to mishandling of ID_UNALLOCATED() registers (solved by consolidating the ID_DESC() macro maze a bit further). Thanks, M.
Since the previous incarnation of the ABI was proved to be subtly wrong, I have reworked it to be more in line with the current way KVM operates. No more late NV-specific adjustment nor writable ID_AA64MMFR0_EL1.VH. The NV configuration is now entirely selected from the vcpu flags. I've preserved the KVM_ARM_VCPU_EL2 flag which enables NV with VHE, and added KVM_ARM_VCPU_EL2_E2H0 which alters the NV behaviour to only allow nVHE guests without recursive NV support. This series is actually very little new code. The bulk of it is converting the feature downgrade to be per-idreg, essentially going back to the state before 44241f34fac96 ("KVM: arm64: nv: Use accessors for modifying ID registers"), only slightly modernised. This then becomes part of the reset value computing. The rest is simply what you'd expect in terms of being able to write the ID_AA64MMFR4_EL1.NV_frac field, making the correct bits RES0 when needed, probing for capabilities and handling the init flags. Patches on top of -rc2, with the integration branch at the usual location. Marc Zyngier (14): arm64: cpufeature: Handle NV_frac as a synonym of NV2 KVM: arm64: Hide ID_AA64MMFR2_EL1.NV from guest and userspace KVM: arm64: Mark HCR.EL2.E2H RES0 when ID_AA64MMFR1_EL1.VH is zero KVM: arm64: Mark HCR.EL2.{NV*,AT} RES0 when ID_AA64MMFR4_EL1.NV_frac is 0 KVM: arm64: Advertise NV2 in the boot messages KVM: arm64: Consolidate idreg reset method KVM: arm64: Make ID_REG_LIMIT_FIELD_ENUM() more widely available KVM: arm64: Enforce NV limits on a per-idregs basis KVM: arm64: Move NV-specific capping to idreg sanitisation KVM: arm64: Allow userspace to limit NV support to nVHE KVM: arm64: Make ID_AA64MMFR4_EL1.NV_frac writable KVM: arm64: Advertise FEAT_ECV when possible KVM: arm64: Allow userspace to request KVM_ARM_VCPU_EL2* KVM: arm64: Document NV caps and vcpu flags Documentation/virt/kvm/api.rst | 14 +- arch/arm64/include/asm/kvm_host.h | 2 +- arch/arm64/include/asm/kvm_nested.h | 1 + arch/arm64/include/uapi/asm/kvm.h | 1 + arch/arm64/kernel/cpufeature.c | 15 +- arch/arm64/kvm/arm.c | 11 +- arch/arm64/kvm/nested.c | 285 +++++++++++++++------------- arch/arm64/kvm/sys_regs.c | 25 +-- arch/arm64/kvm/sys_regs.h | 10 + include/uapi/linux/kvm.h | 2 + 10 files changed, 209 insertions(+), 157 deletions(-)