Re: [PATCH] qemu-kvm: Flush icache after dma operations for ia64

[Avi Kivity <avi@redhat.com>]

Zhang, Xiantao wrote:
>  Avi
>      This is the new patch for icache flush after DMA emualtion for ia64, and it should address Hollis's comments. 
> Xiantao
>
> From 60a27e2ea9758c97e974aa5bb1925ad4ed045c5f Mon Sep 17 00:00:00 2001
> From: Xiantao Zhang <xiantao.zhang@intel.com>
> Date: Mon, 11 May 2009 18:04:15 +0800
> Subject: [PATCH] qemu-kvm: Flush icache after dma operations for ia64
>  
> ia64 system depends on that platform issues snoop cycle to flush
> icache for memory touched by DMA write operations, but virtual DMA
> operations is emulated by memcpy, so use explict instrustions to flush
> the related icache, otherwise, guest may use obsolete icache.
>  
>  
> +#elif defined(__ia64__)
> +static inline void flush_icache_range(unsigned long start, unsigned long stop)
> +{
> +    while (start < stop) {
> + asm volatile ("fc %0" :: "r"(start));
> + start += 32;
> +    }
> +    asm volatile (";;sync.i;;srlz.i;;");
> +}
> +#define qemu_cache_utils_init(envp) do { (void) (envp); } while (0)
>  #else
>  #define qemu_cache_utils_init(envp) do { (void) (envp); } while (0)
>  #endif
> diff --git a/cutils.c b/cutils.c
> index a1652ab..6b7d506 100644
> --- a/cutils.c
> +++ b/cutils.c
> @@ -25,6 +25,10 @@
>  #include "host-utils.h"
>  #include <assert.h>
>  
> +#ifdef __ia64__
> +#include "cache-utils.h"
> +#endif
>   

#includes should be unconditional.

> +
>  void pstrcpy(char *buf, int buf_size, const char *str)
>  {
>      int c;
> @@ -176,6 +180,16 @@ 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);
> +
> + /*ia64 system depends on that platform issues snoop cycle to flush
> + * icache for memory touched by DMA write operations, but virtual DMA
> + * operations is emulated by memcpy, so use explict instrustions to flush
> + * the related icache, otherwise, guest may use obsolete icache. */
> +#ifdef __ia64__
> + flush_icache_range((unsigned long)qiov->iov[i].iov_base,
> +                  (unsigned long)(qiov->iov[i].iov_base + copy));
> +#endif
>   

Instead of the #ifdef, please add a flush_icache_range_after_dma() 
function which does flush_icache_range() for ia64 and nothing for other 
architectures.  This avoids the #ifdef everywhere, and you will only 
need one copy of the comment.

I don't think you need to flush here.  Instead, put the flush in 
cpu_physical_memory_unmap().  Every dma access should invoke that.  If 
you find a path which doesn't, it should be fixed.

>  
> +#ifdef __ia64__
> +#include "cache-utils.h"
> +#endif
>   

Unconditional #include.

> +
>  static AIOPool dma_aio_pool;
>  
>  void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
> @@ -149,6 +153,23 @@ static BlockDriverAIOCB *dma_bdrv_io(
>      dbs->bh = NULL;
>      qemu_iovec_init(&dbs->iov, sg->nsg);
>      dma_bdrv_cb(dbs, 0);
> +
> +    /*ia64 system depends on that platform issues snoop cycle to flush
> +     * icache for memory touched by DMA write operations, but virtual DMA
> +     * operations is emulated by memcpy, so use explict instrustions to flush
> +     * the related icache, otherwise, guest may use obsolete icache. */
> +#ifdef __ia64__
> +    int i;
> +    QEMUIOVector *qiov;
> +    if (!is_write) {
> +        qiov = &dbs->iov;
> +        for (i = 0; i < qiov->niov; ++i) {
> +           flush_icache_range((unsigned long)qiov->iov[i].iov_base,
> +                 (unsigned long)(qiov->iov[i].iov_base + qiov->iov[i].iov_len));
> + }
> +    }
> +#endif
>   

If you move the flush to cpu_physical_memory_unmap(), this can go away.

> +
>      if (!dbs->acb) {
>          qemu_aio_release(dbs);
>          return NULL;
> diff --git a/exec.c b/exec.c
> index 29c91fb..170ede1 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -35,6 +35,7 @@
>  #include "cpu.h"
>  #include "exec-all.h"
>  #include "qemu-common.h"
> +#include "cache-utils.h"
>  
>  #if !defined(TARGET_IA64)
>  #include "tcg.h"
> @@ -3402,8 +3403,12 @@ void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
>                  }
>                  addr1 += l;
>                  access_len -= l;
> -            }
> -        }
> +     }
> +#ifdef TARGET_IA64
> +     flush_icache_range((unsigned long)buffer,
> +       (unsigned long)buffer + access_len);
> +#endif
> +       }
>   

Whitespace damage.

access_len here is zero, so this does nothing.


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