Re: [PATCH 09/12] powerpc: Mark writes registering ipi to host cpu through kvm

[Nicholas Piggin]

On Mon May 8, 2023 at 12:01 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.

How about READ_ONCE for the read side of host_ipi?

Thanks,
Nick

>
> Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com>
> ---
>  arch/powerpc/include/asm/kvm_ppc.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 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
>        *
> -- 
> 2.37.2