From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>

When invalidating memory ranges, if we happen to hit the first
entry in a bucket we were never unmapping it. This was harmless
for foreign mappings but now that we're looking to reuse the
mapcache for transient grant mappings, we must unmap entries
when invalidated.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
---
 hw/xen/xen-mapcache.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
index 4f98d284dd..0365311788 100644
--- a/hw/xen/xen-mapcache.c
+++ b/hw/xen/xen-mapcache.c
@@ -486,18 +486,22 @@ static void xen_invalidate_map_cache_entry_unlocked(MapCache *mc,
         return;
     }
     entry->lock--;
-    if (entry->lock > 0 || pentry == NULL) {
+    if (entry->lock > 0) {
         return;
     }
 
-    pentry->next = entry->next;
     ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size);
     if (munmap(entry->vaddr_base, entry->size) != 0) {
         perror("unmap fails");
         exit(-1);
     }
-    g_free(entry->valid_mapping);
-    g_free(entry);
+    if (pentry) {
+        pentry->next = entry->next;
+        g_free(entry->valid_mapping);
+        g_free(entry);
+    } else {
+        memset(entry, 0, sizeof *entry);
+    }
 }
 
 typedef struct XenMapCacheData {
-- 
2.40.1

On Tue, Apr 30, 2024 at 6:50 PM Edgar E. Iglesias
<edgar.iglesias@gmail.com> wrote:
>
> From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>
>
> When invalidating memory ranges, if we happen to hit the first
> entry in a bucket we were never unmapping it. This was harmless
> for foreign mappings but now that we're looking to reuse the
> mapcache for transient grant mappings, we must unmap entries
> when invalidated.
>
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
> ---
>  hw/xen/xen-mapcache.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
> index 4f98d284dd..0365311788 100644
> --- a/hw/xen/xen-mapcache.c
> +++ b/hw/xen/xen-mapcache.c
> @@ -486,18 +486,22 @@ static void xen_invalidate_map_cache_entry_unlocked(MapCache *mc,
>          return;
>      }
>      entry->lock--;
> -    if (entry->lock > 0 || pentry == NULL) {
> +    if (entry->lock > 0) {
>          return;
>      }
>
> -    pentry->next = entry->next;
>      ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size);
>      if (munmap(entry->vaddr_base, entry->size) != 0) {
>          perror("unmap fails");
>          exit(-1);
>      }
> -    g_free(entry->valid_mapping);
> -    g_free(entry);
> +    if (pentry) {
> +        pentry->next = entry->next;
> +        g_free(entry->valid_mapping);
> +        g_free(entry);
> +    } else {
> +        memset(entry, 0, sizeof *entry);

I noticed that we're leaking entry->valid_mapping here. I'll fix this for v5.

Cheers,
Edgar


> +    }
>  }
>
>  typedef struct XenMapCacheData {
> --
> 2.40.1
>

On Tue, 30 Apr 2024, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>
> 
> When invalidating memory ranges, if we happen to hit the first
> entry in a bucket we were never unmapping it. This was harmless
> for foreign mappings but now that we're looking to reuse the
> mapcache for transient grant mappings, we must unmap entries
> when invalidated.
> 
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
>  hw/xen/xen-mapcache.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
> index 4f98d284dd..0365311788 100644
> --- a/hw/xen/xen-mapcache.c
> +++ b/hw/xen/xen-mapcache.c
> @@ -486,18 +486,22 @@ static void xen_invalidate_map_cache_entry_unlocked(MapCache *mc,
>          return;
>      }
>      entry->lock--;
> -    if (entry->lock > 0 || pentry == NULL) {
> +    if (entry->lock > 0) {
>          return;
>      }
>  
> -    pentry->next = entry->next;
>      ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size);
>      if (munmap(entry->vaddr_base, entry->size) != 0) {
>          perror("unmap fails");
>          exit(-1);
>      }
> -    g_free(entry->valid_mapping);
> -    g_free(entry);
> +    if (pentry) {
> +        pentry->next = entry->next;
> +        g_free(entry->valid_mapping);
> +        g_free(entry);
> +    } else {
> +        memset(entry, 0, sizeof *entry);
> +    }
>  }
>  
>  typedef struct XenMapCacheData {
> -- 
> 2.40.1
>