Introduce vtimer_ctxt_switch_from() and vtimer_ctxt_switch_to() to handle virtual timer state across vCPU context switches.
At present, vtimer_ctxt_switch_from() is a no-op because the RISC-V SSTC extension, which provides a virtualization-aware timer, is not yet supported. Xen therefore relies the virtual (SBI-based) timer. The virtual timer uses Xen's internal timer infrastructure and must be associated with the pCPU on which the vCPU is currently running so that timer events can be delivered efficiently. As a result, vtimer_ctxt_switch_to() migrates the timer to the target pCPU when a vCPU is scheduled in. Signed-off-by: Oleksii Kurochko <[email protected]> Acked-by: Jan Beulich <[email protected]> --- Changes in v3: - s/vtimer_ctx_switch_to/vtimer_ctxt_switch_to - s/vtimer_ctx_switch_from/vtimer_ctxt_switch_from - Add Acked-by: Jan Beulich <[email protected]>. --- Changes in v2: - Align the parameters names for vtimer_ctx_switch_from() and vtimer_ctx_switch_to() in declarations to match the ones in the defintions to make Misra happy. - s/vtimer_save/vtimer_ctx_switch_from. - s/vtimer_restore/vtimer_ctx_switch_to. - Update the commit message. --- xen/arch/riscv/include/asm/vtimer.h | 3 +++ xen/arch/riscv/vtimer.c | 15 +++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/xen/arch/riscv/include/asm/vtimer.h b/xen/arch/riscv/include/asm/vtimer.h index 0d1555511755..c70b0226515e 100644 --- a/xen/arch/riscv/include/asm/vtimer.h +++ b/xen/arch/riscv/include/asm/vtimer.h @@ -17,4 +17,7 @@ void vcpu_timer_destroy(struct vcpu *v); void vtimer_set_timer(struct vtimer *t, uint64_t ticks); +void vtimer_ctxt_switch_from(struct vcpu *p); +void vtimer_ctxt_switch_to(struct vcpu *n); + #endif /* ASM__RISCV__VTIMER_H */ diff --git a/xen/arch/riscv/vtimer.c b/xen/arch/riscv/vtimer.c index 32d142bcdfcd..afd8a53a7387 100644 --- a/xen/arch/riscv/vtimer.c +++ b/xen/arch/riscv/vtimer.c @@ -1,5 +1,6 @@ /* SPDX-License-Identifier: GPL-2.0-only */ +#include <xen/bug.h> #include <xen/sched.h> #include <xen/timer.h> @@ -69,3 +70,17 @@ void vtimer_set_timer(struct vtimer *t, const uint64_t ticks) migrate_timer(&t->timer, smp_processor_id()); set_timer(&t->timer, expires); } + +void vtimer_ctxt_switch_from(struct vcpu *p) +{ + ASSERT(!is_idle_vcpu(p)); + + /* Nothing to do at the moment as SSTC isn't supported now. */ +} + +void vtimer_ctxt_switch_to(struct vcpu *n) +{ + ASSERT(!is_idle_vcpu(n)); + + migrate_timer(&n->arch.vtimer.timer, n->processor); +} -- 2.52.0
