Re: [PATCH] KVM: Qemu: Flush i-cache after ide-dma operation in IA64

[Avi Kivity <avi@redhat.com>]

Zhang, Yang wrote:
> The data from dma will include instructions. In order to exeuting the right
> instruction, we should to flush the i-cache to ensure those data can be see 
> by cpu.
>
>
>
> diff --git a/qemu/cache-utils.h b/qemu/cache-utils.h
> index b45fde4..5e11d12 100644
> --- a/qemu/cache-utils.h
> +++ b/qemu/cache-utils.h
> @@ -33,8 +33,22 @@ static inline void flush_icache_range(unsigned long start, unsigned long stop)
>      asm volatile ("sync" : : : "memory");
>      asm volatile ("isync" : : : "memory");
>  }
> +#define qemu_sync_idcache flush_icache_range
> +#else
>  
> +#ifdef __ia64__
> +static inline void qemu_sync_idcache(unsigned long start, unsigned long stop)
> +{
> +    while (start < stop) {
> +	    asm volatile ("fc %0" :: "r"(start));
> +	    start += 32;
> +    }
> +    asm volatile (";;sync.i;;srlz.i;;");
> +}
>   

What about smp?

I'm surprised the guest doesn't do this by itself?

>  
>  void pstrcpy(char *buf, int buf_size, const char *str)
> @@ -215,6 +216,8 @@ void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count)
>          if (copy > qiov->iov[i].iov_len)
>              copy = qiov->iov[i].iov_len;
>          memcpy(qiov->iov[i].iov_base, p, copy);
> +        qemu_sync_idcache((unsigned long)qiov->iov[i].iov_base, 
> +                    (unsigned long)(qiov->iov[i].iov_base + copy));
>          p     += copy;
>          count -= copy;
>      }
>   

This is the wrong place to put this.  Once we stop bouncing 
scatter/gather DMA, we will no longer call this function.

The correct place is either in the device code itself, or in the dma api 
(dma-helpers.c).


-- 
error compiling committee.c: too many arguments to function