On Wed May 10, 2023 at 1:31 PM AEST, Rohan McLure wrote:
> Mark writes to hypervisor ipi state so that KCSAN recognises these
> asynchronous issue of kvmppc_{set,clear}_host_ipi to be intended, with
> atomic writes. Mark asynchronous polls to this variable in
> kvm_ppc_read_one_intr().
>
> Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com>
What's the go with accesses in asm? Does it just assume you know
what you're doing?
Reviewed-by: Nicholas Piggin <npig...@gmail.com>
> ---
> v2: Add read-side annotations to both polling locations in
> kvm_ppc_read_one_intr().
> ---
> arch/powerpc/include/asm/kvm_ppc.h | 4 ++--
> arch/powerpc/kvm/book3s_hv_builtin.c | 4 ++--
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h
> b/arch/powerpc/include/asm/kvm_ppc.h
> index bc57d058ad5b..d701df006c08 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -548,12 +548,12 @@ static inline void kvmppc_set_host_ipi(int cpu)
> * pairs with the barrier in kvmppc_clear_host_ipi()
> */
> smp_mb();
> - paca_ptrs[cpu]->kvm_hstate.host_ipi = 1;
> + WRITE_ONCE(paca_ptrs[cpu]->kvm_hstate.host_ipi, 1);
> }
>
> static inline void kvmppc_clear_host_ipi(int cpu)
> {
> - paca_ptrs[cpu]->kvm_hstate.host_ipi = 0;
> + WRITE_ONCE(paca_ptrs[cpu]->kvm_hstate.host_ipi, 0);
> /*
> * order clearing of host_ipi flag vs. processing of IPI messages
> *
> diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c
> b/arch/powerpc/kvm/book3s_hv_builtin.c
> index da85f046377a..0f5b021fa559 100644
> --- a/arch/powerpc/kvm/book3s_hv_builtin.c
> +++ b/arch/powerpc/kvm/book3s_hv_builtin.c
> @@ -406,7 +406,7 @@ static long kvmppc_read_one_intr(bool *again)
> return 1;
>
> /* see if a host IPI is pending */
> - host_ipi = local_paca->kvm_hstate.host_ipi;
> + host_ipi = READ_ONCE(local_paca->kvm_hstate.host_ipi);
> if (host_ipi)
> return 1;
>
> @@ -466,7 +466,7 @@ static long kvmppc_read_one_intr(bool *again)
> * meantime. If it's clear, we bounce the interrupt to the
> * guest
> */
> - host_ipi = local_paca->kvm_hstate.host_ipi;
> + host_ipi = READ_ONCE(local_paca->kvm_hstate.host_ipi);
> if (unlikely(host_ipi != 0)) {
> /* We raced with the host,
> * we need to resend that IPI, bummer
> --
> 2.37.2
