[PATCH v7 00/14] xen/riscv: introduce vtimer related things

[Oleksii Kurochko <oleksii.kurochko@gmail.com>]

This patch series introduces the components necessary to implement a virtual
timer (vtimer).

Since the SSTC extension is not supported by Xen, an emulated (SBI-based)
timer is required. To address this, a virtual timer built on Xen’s timer
infrastructure is introduced, with save/restore support and SBI-based
programming.

To provide full guest software–based timer support, the following components
are also introduced:
- arch_vcpu_{create,destroy}() to initialize the virtual timer and other
  vCPU-related state not directly tied to timer functionality. As part of this
  work, struct arch_vcpu is introduced to describe the internal state of a
  virtual CPU, along with vcpu_csr_init() to initialize the relevant CSR state.
- Support functions required by the virtual timer, including:
  - vcpu_kick(), and a stub implementation of smp_send_event_check_mask()
    (since SMP is not yet supported in Xen), which is used by vcpu_kick().
  - Support for guest timer programming via interception of the SBI legacy
    SET_TIMER call from guest.
  - Implement reprogram_timer() using introduced sbi_set_timer().
  - Initial lockless tracking of pending vCPU interrupts using atomic bitmaps.
- Handling of hypervisor timer interrupts and dispatch into Xen’s generic timer
  softirq.

CI tests: https://gitlab.com/xen-project/people/olkur/xen/-/pipelines/2368929819
---
Changes in v7:
 - Merged to upstream/staging:
   - xen/time: move ticks<->ns helpers to common code
 - Add Acked-by for Patch 2: xen/riscv: implement vcpu_csr_init().
 - Address comments from ML for patch 1 and 3.
 - Add new patch to detect availabilty of SSTC. IMO, it is okay to have this
   patch separetely as at the moment it won't be an issue if Xen will use
   CSR_STIMECMP to setup its timer. The issue will start to occur when a guest
   will run.
---
Changes in v6:
 - Address comments from ML for patch 1 and 3, and minor update of patch 2
   because of introduced ro_one sub-struct in patch 1.
---
Changes in v5:
 - Merged to upstream/staging:
     xen/riscv: implement arch_vcpu_{create,destroy}()
     xen/riscv: build setup code as .init
 - Rebase this patch series on top of:
     https://lore.kernel.org/xen-devel/5756356294dc066d835269334d0f3347fe24cec4.1771504676.git.oleksii.kurochko@gmail.com/T/#u
   There is no logical dependency, only the potential merge conflict question.
 - Address comments from ML.
---
Changes in v4:
 - Merged to upstream/staging:
     xen/riscv: avoid reading hstateen0 when Smstateen is not implemented
 - Address other comments from ML.
---
Changes in v3:
 - Squash patch "xen/riscv: introduce struct arch_vcpu" into other
   patches of the patch series.
 - Merged to staging:
   - xen/riscv: implement stub for smp_send_event_check_mask()
 - Address other comments from ML.
---
Changes in v2:
 - Add consumer part of tracking of pending vCPU interrupts.
 - Split patch "xen/riscv: init tasklet subsystem" to two.
 - Patches were acked:
   - xen/riscv: introduce vcpu_kick() implementation
   - xen/riscv: implement SBI legacy SET_TIMER support for guests
 - All other changes are patch-specific. Please check them.
---

Oleksii Kurochko (14):
  xen/riscv: detect and store supported hypervisor CSR bits at boot
  xen/riscv: implement vcpu_csr_init()
  xen/riscv: introduce tracking of pending vCPU interrupts, part 1
  xen/riscv: introduce tracking of pending vCPU interrupts, part 2
  xen/riscv: introduce basic vtimer infrastructure for guests
  xen/riscv: introduce vcpu_kick() implementation
  xen/riscv: add vtimer context switch helpers
  xen/riscv: implement SBI legacy SET_TIMER support for guests
  xen/riscv: introduce sbi_set_timer()
  xen/riscv: implement reprogram_timer() via SBI
  xen/riscv: handle hypervisor timer interrupts
  xen/riscv: init tasklet subsystem
  xen/riscv: implement sync_vcpu_execstate()
  xen/riscv: Disable SSTC extension and add trap-based CSR probing

 automation/scripts/qemu-smoke-riscv64.sh    |   2 +-
 xen/arch/riscv/Makefile                     |   1 +
 xen/arch/riscv/cpufeature.c                 |   8 +
 xen/arch/riscv/domain.c                     | 244 +++++++++++++++++++-
 xen/arch/riscv/entry.S                      |  24 ++
 xen/arch/riscv/include/asm/Makefile         |   1 -
 xen/arch/riscv/include/asm/csr.h            |  32 +++
 xen/arch/riscv/include/asm/current.h        |   2 +
 xen/arch/riscv/include/asm/domain.h         |  32 +++
 xen/arch/riscv/include/asm/perfc_defn.h     |   3 +
 xen/arch/riscv/include/asm/riscv_encoding.h |   2 +
 xen/arch/riscv/include/asm/sbi.h            |  22 ++
 xen/arch/riscv/include/asm/setup.h          |   2 +
 xen/arch/riscv/include/asm/traps.h          |   7 +
 xen/arch/riscv/include/asm/vtimer.h         |  20 ++
 xen/arch/riscv/riscv64/asm-offsets.c        |   7 +-
 xen/arch/riscv/sbi.c                        |  40 +++-
 xen/arch/riscv/setup.c                      |   5 +
 xen/arch/riscv/stubs.c                      |  20 --
 xen/arch/riscv/time.c                       |  43 ++++
 xen/arch/riscv/traps.c                      |  20 ++
 xen/arch/riscv/vsbi/legacy-extension.c      |   6 +
 xen/arch/riscv/vtimer.c                     |  86 +++++++
 23 files changed, 603 insertions(+), 26 deletions(-)
 create mode 100644 xen/arch/riscv/include/asm/perfc_defn.h
 create mode 100644 xen/arch/riscv/include/asm/vtimer.h
 create mode 100644 xen/arch/riscv/vtimer.c

-- 
2.53.0