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[QEMU][PATCH v3 3/7] softmmu: let qemu_map_ram_ptr() use qemu_ram_ptr_length()

Vikram Garhwal posted 7 patches 1 year, 11 months ago
[QEMU][PATCH v3 3/7] softmmu: let qemu_map_ram_ptr() use qemu_ram_ptr_length()
Posted by Vikram Garhwal 1 year, 11 months ago 
From: Juergen Gross <jgross@suse.com>

qemu_map_ram_ptr() and qemu_ram_ptr_length() share quite some code, so
modify qemu_ram_ptr_length() a little bit and use it for
qemu_map_ram_ptr(), too.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
 system/physmem.c | 56 ++++++++++++++++++++----------------------------
 1 file changed, 23 insertions(+), 33 deletions(-)

diff --git a/system/physmem.c b/system/physmem.c
index 84f3022099..949dcb20ba 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -2163,43 +2163,17 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
 }
 #endif /* !_WIN32 */
 
-/* Return a host pointer to ram allocated with qemu_ram_alloc.
- * This should not be used for general purpose DMA.  Use address_space_map
- * or address_space_rw instead. For local memory (e.g. video ram) that the
- * device owns, use memory_region_get_ram_ptr.
- *
- * Called within RCU critical section.
- */
-void *qemu_map_ram_ptr(RAMBlock *block, ram_addr_t addr)
-{
-    if (block == NULL) {
-        block = qemu_get_ram_block(addr);
-        addr -= block->offset;
-    }
-
-    if (xen_enabled() && block->host == NULL) {
-        /* We need to check if the requested address is in the RAM
-         * because we don't want to map the entire memory in QEMU.
-         * In that case just map until the end of the page.
-         */
-        if (block->offset == 0) {
-            return xen_map_cache(addr, 0, 0, false);
-        }
-
-        block->host = xen_map_cache(block->offset, block->max_length, 1, false);
-    }
-    return ramblock_ptr(block, addr);
-}
-
-/* Return a host pointer to guest's ram. Similar to qemu_map_ram_ptr
- * but takes a size argument.
+/*
+ * Return a host pointer to guest's ram.
  *
  * Called within RCU critical section.
  */
 static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
                                  hwaddr *size, bool lock)
 {
-    if (*size == 0) {
+    hwaddr len = 0;
+
+    if (size && *size == 0) {
         return NULL;
     }
 
@@ -2207,7 +2181,10 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
         block = qemu_get_ram_block(addr);
         addr -= block->offset;
     }
-    *size = MIN(*size, block->max_length - addr);
+    if (size) {
+        *size = MIN(*size, block->max_length - addr);
+        len = *size;
+    }
 
     if (xen_enabled() && block->host == NULL) {
         /* We need to check if the requested address is in the RAM
@@ -2215,7 +2192,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
          * In that case just map the requested area.
          */
         if (block->offset == 0) {
-            return xen_map_cache(addr, *size, lock, lock);
+            return xen_map_cache(addr, len, lock, lock);
         }
 
         block->host = xen_map_cache(block->offset, block->max_length, 1, lock);
@@ -2224,6 +2201,19 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
     return ramblock_ptr(block, addr);
 }
 
+/*
+ * Return a host pointer to ram allocated with qemu_ram_alloc.
+ * This should not be used for general purpose DMA.  Use address_space_map
+ * or address_space_rw instead. For local memory (e.g. video ram) that the
+ * device owns, use memory_region_get_ram_ptr.
+ *
+ * Called within RCU critical section.
+ */
+void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr)
+{
+    return qemu_ram_ptr_length(ram_block, addr, NULL, false);
+}
+
 /* Return the offset of a hostpointer within a ramblock */
 ram_addr_t qemu_ram_block_host_offset(RAMBlock *rb, void *host)
 {
-- 
2.17.1
Re: [QEMU][PATCH v3 3/7] softmmu: let qemu_map_ram_ptr() use qemu_ram_ptr_length()
Posted by Edgar E. Iglesias 1 year, 10 months ago 
On Tue, Feb 27, 2024 at 11:37 PM Vikram Garhwal <vikram.garhwal@amd.com>
wrote:

> From: Juergen Gross <jgross@suse.com>
>
> qemu_map_ram_ptr() and qemu_ram_ptr_length() share quite some code, so
> modify qemu_ram_ptr_length() a little bit and use it for
> qemu_map_ram_ptr(), too.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
>

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>




> ---
>  system/physmem.c | 56 ++++++++++++++++++++----------------------------
>  1 file changed, 23 insertions(+), 33 deletions(-)
>
> diff --git a/system/physmem.c b/system/physmem.c
> index 84f3022099..949dcb20ba 100644
> --- a/system/physmem.c
> +++ b/system/physmem.c
> @@ -2163,43 +2163,17 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t
> length)
>  }
>  #endif /* !_WIN32 */
>
> -/* Return a host pointer to ram allocated with qemu_ram_alloc.
> - * This should not be used for general purpose DMA.  Use address_space_map
> - * or address_space_rw instead. For local memory (e.g. video ram) that the
> - * device owns, use memory_region_get_ram_ptr.
> - *
> - * Called within RCU critical section.
> - */
> -void *qemu_map_ram_ptr(RAMBlock *block, ram_addr_t addr)
> -{
> -    if (block == NULL) {
> -        block = qemu_get_ram_block(addr);
> -        addr -= block->offset;
> -    }
> -
> -    if (xen_enabled() && block->host == NULL) {
> -        /* We need to check if the requested address is in the RAM
> -         * because we don't want to map the entire memory in QEMU.
> -         * In that case just map until the end of the page.
> -         */
> -        if (block->offset == 0) {
> -            return xen_map_cache(addr, 0, 0, false);
> -        }
> -
> -        block->host = xen_map_cache(block->offset, block->max_length, 1,
> false);
> -    }
> -    return ramblock_ptr(block, addr);
> -}
> -
> -/* Return a host pointer to guest's ram. Similar to qemu_map_ram_ptr
> - * but takes a size argument.
> +/*
> + * Return a host pointer to guest's ram.
>   *
>   * Called within RCU critical section.
>   */
>  static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
>                                   hwaddr *size, bool lock)
>  {
> -    if (*size == 0) {
> +    hwaddr len = 0;
> +
> +    if (size && *size == 0) {
>          return NULL;
>      }
>
> @@ -2207,7 +2181,10 @@ static void *qemu_ram_ptr_length(RAMBlock *block,
> ram_addr_t addr,
>          block = qemu_get_ram_block(addr);
>          addr -= block->offset;
>      }
> -    *size = MIN(*size, block->max_length - addr);
> +    if (size) {
> +        *size = MIN(*size, block->max_length - addr);
> +        len = *size;
> +    }
>
>      if (xen_enabled() && block->host == NULL) {
>          /* We need to check if the requested address is in the RAM
> @@ -2215,7 +2192,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block,
> ram_addr_t addr,
>           * In that case just map the requested area.
>           */
>          if (block->offset == 0) {
> -            return xen_map_cache(addr, *size, lock, lock);
> +            return xen_map_cache(addr, len, lock, lock);
>          }
>
>          block->host = xen_map_cache(block->offset, block->max_length, 1,
> lock);
> @@ -2224,6 +2201,19 @@ static void *qemu_ram_ptr_length(RAMBlock *block,
> ram_addr_t addr,
>      return ramblock_ptr(block, addr);
>  }
>
> +/*
> + * Return a host pointer to ram allocated with qemu_ram_alloc.
> + * This should not be used for general purpose DMA.  Use address_space_map
> + * or address_space_rw instead. For local memory (e.g. video ram) that the
> + * device owns, use memory_region_get_ram_ptr.
> + *
> + * Called within RCU critical section.
> + */
> +void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr)
> +{
> +    return qemu_ram_ptr_length(ram_block, addr, NULL, false);
> +}
> +
>  /* Return the offset of a hostpointer within a ramblock */
>  ram_addr_t qemu_ram_block_host_offset(RAMBlock *rb, void *host)
>  {
> --
> 2.17.1
>
>
>
Re: [QEMU][PATCH v3 3/7] softmmu: let qemu_map_ram_ptr() use qemu_ram_ptr_length()
Posted by Alex Bennée 1 year, 11 months ago 
Vikram Garhwal <vikram.garhwal@amd.com> writes:

> From: Juergen Gross <jgross@suse.com>
>
> qemu_map_ram_ptr() and qemu_ram_ptr_length() share quite some code, so
> modify qemu_ram_ptr_length() a little bit and use it for
> qemu_map_ram_ptr(), too.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> ---
>  system/physmem.c | 56 ++++++++++++++++++++----------------------------
>  1 file changed, 23 insertions(+), 33 deletions(-)
>
<snip>
> -
> -/* Return a host pointer to guest's ram. Similar to qemu_map_ram_ptr
> - * but takes a size argument.
> +/*
> + * Return a host pointer to guest's ram.
>   *
>   * Called within RCU critical section.
>   */

If you end up re-spinning it would be nice to kdoc this function and at
least call out size as a return by ref and optional. 

>  static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
>                                   hwaddr *size, bool lock)
>  {
> -    if (*size == 0) {
> +    hwaddr len = 0;
> +
> +    if (size && *size == 0) {
>          return NULL;
>      }
>  
> @@ -2207,7 +2181,10 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
>          block = qemu_get_ram_block(addr);
>          addr -= block->offset;
>      }
> -    *size = MIN(*size, block->max_length - addr);
> +    if (size) {
> +        *size = MIN(*size, block->max_length - addr);
> +        len = *size;
> +    }
>  
>      if (xen_enabled() && block->host == NULL) {
>          /* We need to check if the requested address is in the RAM
> @@ -2215,7 +2192,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
>           * In that case just map the requested area.
>           */
>          if (block->offset == 0) {
> -            return xen_map_cache(addr, *size, lock, lock);
> +            return xen_map_cache(addr, len, lock, lock);

I did wonder if len == 0 will confuse things but it seems xen_map_cache
will default to XC_PAGE_SIZE in that case.

Anyway:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro
Re: [QEMU][PATCH v3 3/7] softmmu: let qemu_map_ram_ptr() use qemu_ram_ptr_length()
Posted by Vikram Garhwal 1 year, 11 months ago 
On Fri, Mar 01, 2024 at 05:04:54PM +0000, Alex Bennée wrote:
> Vikram Garhwal <vikram.garhwal@amd.com> writes:
> 
> > From: Juergen Gross <jgross@suse.com>
> >
> > qemu_map_ram_ptr() and qemu_ram_ptr_length() share quite some code, so
> > modify qemu_ram_ptr_length() a little bit and use it for
> > qemu_map_ram_ptr(), too.
> >
> > Signed-off-by: Juergen Gross <jgross@suse.com>
> > Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
> > Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> > ---
> >  system/physmem.c | 56 ++++++++++++++++++++----------------------------
> >  1 file changed, 23 insertions(+), 33 deletions(-)
> >
> <snip>
> > -
> > -/* Return a host pointer to guest's ram. Similar to qemu_map_ram_ptr
> > - * but takes a size argument.
> > +/*
> > + * Return a host pointer to guest's ram.
> >   *
> >   * Called within RCU critical section.
> >   */
> 
> If you end up re-spinning it would be nice to kdoc this function and at
> least call out size as a return by ref and optional. 
Will do if re-spinning is needed.
> 
> >  static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
> >                                   hwaddr *size, bool lock)
> >  {
> > -    if (*size == 0) {
> > +    hwaddr len = 0;
> > +
> > +    if (size && *size == 0) {
> >          return NULL;
> >      }
> >  
> > @@ -2207,7 +2181,10 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
> >          block = qemu_get_ram_block(addr);
> >          addr -= block->offset;
> >      }
> > -    *size = MIN(*size, block->max_length - addr);
> > +    if (size) {
> > +        *size = MIN(*size, block->max_length - addr);
> > +        len = *size;
> > +    }
> >  
> >      if (xen_enabled() && block->host == NULL) {
> >          /* We need to check if the requested address is in the RAM
> > @@ -2215,7 +2192,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
> >           * In that case just map the requested area.
> >           */
> >          if (block->offset == 0) {
> > -            return xen_map_cache(addr, *size, lock, lock);
> > +            return xen_map_cache(addr, len, lock, lock);
> 
> I did wonder if len == 0 will confuse things but it seems xen_map_cache
> will default to XC_PAGE_SIZE in that case.
> 
> Anyway:
> 
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> 
> -- 
> Alex Bennée
> Virtualisation Tech Lead @ Linaro

Patchew 2.1-devel-8c64711

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