| Message ID | 20230605064848.12319-1-jpn@linux.vnet.ibm.com |
|---|---|
| Headers | show |
| Series | KVM: PPC: Nested PAPR guests | expand |
On Mon Jun 5, 2023 at 4:48 PM AEST, Jordan Niethe wrote: > There is existing support for nested guests on powernv hosts however the > hcall interface this uses is not support by other PAPR hosts. I kind of liked it being called nested-HV v1 and v2 APIs as short and to the point, but I suppose that's ambiguous with version 2 of the v1 API, so papr is okay. What's the old API called in this scheme, then? "Existing API" is not great after patches go upstream. And, you've probably explained it pretty well but slightly more of a background first up could be helpful. E.g., A nested-HV API for PAPR has been developed based on the KVM-specific nested-HV API that is upstream in Linux/KVM and QEMU. The PAPR API had to break compatibility to accommodate implementation in other hypervisors and partitioning firmware. And key overall differences The control flow and interrupt processing between L0, L1, and L2 in the new PAPR API are conceptually unchanged. Where the old API is almost stateless, the PAPR API is stateful, with the L1 registering L2 virtual machines and vCPUs with the L0. Supervisor-privileged register switching duty is now the responsibility for the L0, which holds canonical L2 register state and handles all switching. This new register handling motivates the "getters and setters" wrappers ... Thanks, Nick
On Wed, Jun 7, 2023 at 3:54 PM Nicholas Piggin <npiggin@gmail.com> wrote: > > On Mon Jun 5, 2023 at 4:48 PM AEST, Jordan Niethe wrote: > > There is existing support for nested guests on powernv hosts however the > > hcall interface this uses is not support by other PAPR hosts. > > I kind of liked it being called nested-HV v1 and v2 APIs as short and > to the point, but I suppose that's ambiguous with version 2 of the v1 > API, so papr is okay. What's the old API called in this scheme, then? > "Existing API" is not great after patches go upstream. Yes I was trying for a more descriptive name but it is just more confusing and I'm struggling for a better alternative. In the next revision I'll use v1 and v2. For version 2 of v1 we now call it v1.2 or something like that? > > And, you've probably explained it pretty well but slightly more of > a background first up could be helpful. E.g., > > A nested-HV API for PAPR has been developed based on the KVM-specific > nested-HV API that is upstream in Linux/KVM and QEMU. The PAPR API > had to break compatibility to accommodate implementation in other > hypervisors and partitioning firmware. > > And key overall differences > > The control flow and interrupt processing between L0, L1, and L2 > in the new PAPR API are conceptually unchanged. Where the old API > is almost stateless, the PAPR API is stateful, with the L1 registering > L2 virtual machines and vCPUs with the L0. Supervisor-privileged > register switching duty is now the responsibility for the L0, which > holds canonical L2 register state and handles all switching. This > new register handling motivates the "getters and setters" wrappers > ... I'll include something along those lines. Thanks, Jordan > > Thanks, > Nick >
There is existing support for nested guests on powernv hosts however the hcall interface this uses is not support by other PAPR hosts. A set of new hcalls will be added to PAPR to facilitate creating and managing guests by a regular partition in the following way: - L1 and L0 negotiate capabilities with H_GUEST_{G,S}ET_CAPABILITIES - L1 requests the L0 create a L2 with H_GUEST_CREATE and receives a handle to use in future hcalls - L1 requests the L0 create a L2 vCPU with H_GUEST_CREATE_VCPU - L1 sets up the L2 using H_GUEST_SET and the H_GUEST_VCPU_RUN input buffer - L1 requests the L0 runs the L2 vCPU using H_GUEST_VCPU_RUN - L2 returns to L1 with an exit reason and L1 reads the H_GUEST_VCPU_RUN output buffer populated by the L0 - L1 handles the exit using H_GET_STATE if necessary - L1 reruns L2 vCPU with H_GUEST_VCPU_RUN - L1 frees the L2 in the L0 with H_GUEST_DELETE Further details are available in Documentation/powerpc/kvm-nested.rst. This series adds KVM support for using this hcall interface as a regular PAPR partition, i.e. the L1. It does not add support for running as the L0. The new hcalls have been implemented in the spapr qemu model for testing. This is available at https://github.com/mikey/qemu/tree/kvm-papr There are scripts available to assist in setting up an environment for testing nested guests at https://github.com/mikey/kvm-powervm-test A tree with this series is available at https://github.com/iamjpn/linux/tree/features/kvm-papr Thanks to Amit Machhiwal, Kautuk Consul, Vaibhav Jain, Michael Neuling, Shivaprasad Bhat, Harsh Prateek Bora, Paul Mackerras and Nicholas Piggin. Change overview in v2: - Rebase on top of kvm ppc prefix instruction support - Make documentation an individual patch - Move guest state buffer files from arch/powerpc/lib/ to arch/powerpc/kvm/ - Use kunit for testing guest state buffer - Fix some build errors - Change HEIR element from 4 bytes to 8 bytes Previous revisions: - v1: https://lore.kernel.org/linuxppc-dev/20230508072332.2937883-1-jpn@linux.vnet.ibm.com/ Jordan Niethe (5): KVM: PPC: Use getters and setters for vcpu register state KVM: PPC: Add fpr getters and setters KVM: PPC: Add vr getters and setters KVM: PPC: Add helper library for Guest State Buffers KVM: PPC: Add support for nested PAPR guests Michael Neuling (1): docs: powerpc: Document nested KVM on POWER Documentation/powerpc/index.rst | 1 + Documentation/powerpc/kvm-nested.rst | 636 +++++++++++ arch/powerpc/Kconfig.debug | 12 + arch/powerpc/include/asm/guest-state-buffer.h | 988 ++++++++++++++++++ arch/powerpc/include/asm/hvcall.h | 30 + arch/powerpc/include/asm/kvm_book3s.h | 205 +++- arch/powerpc/include/asm/kvm_book3s_64.h | 6 + arch/powerpc/include/asm/kvm_booke.h | 10 + arch/powerpc/include/asm/kvm_host.h | 21 + arch/powerpc/include/asm/kvm_ppc.h | 80 +- arch/powerpc/include/asm/plpar_wrappers.h | 198 ++++ arch/powerpc/kvm/Makefile | 4 + arch/powerpc/kvm/book3s.c | 38 +- arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 +- arch/powerpc/kvm/book3s_64_mmu_radix.c | 9 +- arch/powerpc/kvm/book3s_64_vio.c | 4 +- arch/powerpc/kvm/book3s_hv.c | 336 ++++-- arch/powerpc/kvm/book3s_hv.h | 65 ++ arch/powerpc/kvm/book3s_hv_builtin.c | 10 +- arch/powerpc/kvm/book3s_hv_nested.c | 38 +- arch/powerpc/kvm/book3s_hv_p9_entry.c | 4 +- arch/powerpc/kvm/book3s_hv_papr.c | 940 +++++++++++++++++ arch/powerpc/kvm/book3s_hv_ras.c | 5 +- arch/powerpc/kvm/book3s_hv_rm_mmu.c | 8 +- arch/powerpc/kvm/book3s_hv_rm_xics.c | 4 +- arch/powerpc/kvm/book3s_xive.c | 9 +- arch/powerpc/kvm/emulate_loadstore.c | 6 +- arch/powerpc/kvm/guest-state-buffer.c | 612 +++++++++++ arch/powerpc/kvm/powerpc.c | 76 +- arch/powerpc/kvm/test-guest-state-buffer.c | 321 ++++++ 30 files changed, 4467 insertions(+), 213 deletions(-) create mode 100644 Documentation/powerpc/kvm-nested.rst create mode 100644 arch/powerpc/include/asm/guest-state-buffer.h create mode 100644 arch/powerpc/kvm/book3s_hv_papr.c create mode 100644 arch/powerpc/kvm/guest-state-buffer.c create mode 100644 arch/powerpc/kvm/test-guest-state-buffer.c