Re: [Xen-devel] [PATCH] Fix invalidate if memory requested was not bucket aligned

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 7 Aug 2012, Frediano Ziglio wrote:
> When memory is mapped in qemu_map_cache with lock != 0 a reverse mapping
> is created pointing to the virtual address of location requested.
> The cached mapped entry is saved in last_address_vaddr with the memory
> location of the base virtual address (without bucket offset).
> However when this entry is invalidated the virtual address saved in the
> reverse mapping is used. This cause that the mapping is freed but the
> last_address_vaddr is not reset.
> 
> Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>

Could you please send a patch for upstream QEMU too?


> ---
>  hw/xen_machine_fv.c |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/xen_machine_fv.c b/hw/xen_machine_fv.c
> index fdad42a..b385d6a 100644
> --- a/hw/xen_machine_fv.c
> +++ b/hw/xen_machine_fv.c
> @@ -181,9 +181,6 @@ void qemu_invalidate_entry(uint8_t *buffer)
>      unsigned long paddr_index;
>      int found = 0;
>      
> -    if (last_address_vaddr == buffer)
> -        last_address_page =  ~0UL;
> -
>      TAILQ_FOREACH(reventry, &locked_entries, next) {
>          if (reventry->vaddr_req == buffer) {
>              paddr_index = reventry->paddr_index;
> @@ -201,6 +198,10 @@ void qemu_invalidate_entry(uint8_t *buffer)
>      TAILQ_REMOVE(&locked_entries, reventry, next);
>      qemu_free(reventry);
>  
> +    if (last_address_page >> (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT) == 
> paddr_index) {
> +        last_address_page =  ~0UL;
> +    }

code style: I wouldn't mind a pair of parentesys around
(last_address_page >> (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT), also max 80
columns.
Other than that is OK.


>      entry = &mapcache_entry[paddr_index % nr_buckets];
>      while (entry && entry->paddr_index != paddr_index) {
>          pentry = entry;



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