The scheduler may call this function to force synchronization of given vCPU's state. Although RISC-V does not support lazy context switching, a full memory barrier is still required to order observation of the saved context correctly.
Signed-off-by: Oleksii Kurochko <[email protected]> --- Changes in v2: - New patch. --- xen/arch/riscv/domain.c | 18 ++++++++++++++++++ xen/arch/riscv/stubs.c | 5 ----- 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/xen/arch/riscv/domain.c b/xen/arch/riscv/domain.c index 1458902aff82..48ba7584acaa 100644 --- a/xen/arch/riscv/domain.c +++ b/xen/arch/riscv/domain.c @@ -259,3 +259,21 @@ void sync_local_execstate(void) { /* Nothing to do -- no lazy switching */ } + +void sync_vcpu_execstate(struct vcpu *v) +{ + /* + * We don't support lazy switching. + * + * However the context may have been saved from a remote pCPU so we + * need a barrier to ensure it is observed before continuing. + * + * Per vcpu_context_saved(), the context can be observed when + * v->is_running is false (the caller should check it before calling + * this function). + * + * Note this is a full barrier to also prevent update of the context + * to happen before it was observed. + */ + smp_mb(); +} diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c index c912d46f1e42..26434166acc6 100644 --- a/xen/arch/riscv/stubs.c +++ b/xen/arch/riscv/stubs.c @@ -91,11 +91,6 @@ void continue_running(struct vcpu *same) BUG_ON("unimplemented"); } -void sync_vcpu_execstate(struct vcpu *v) -{ - BUG_ON("unimplemented"); -} - void startup_cpu_idle_loop(void) { BUG_ON("unimplemented"); -- 2.52.0
