Re: [QEMU][PATCH v1 3/7] softmmu: let qemu_map_ram_ptr() use qemu_ram_ptr_length()

[Vikram Garhwal <vikram.garhwal@amd.com>]

On Mon, Oct 09, 2023 at 05:10:43PM -0700, Stefano Stabellini wrote:
> On Thu, 5 Oct 2023, Vikram Garhwal 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>
> 
> This patch also doesn't apply due to code movement.
Will rebase it.
> 
> Other than that, the patch looks good to me
> 
> 
> > ---
> >  softmmu/physmem.c | 58 +++++++++++++++++++----------------------------
> >  1 file changed, 23 insertions(+), 35 deletions(-)
> > 
> > diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> > index e182a2fa07..6e5e379dd0 100644
> > --- a/softmmu/physmem.c
> > +++ b/softmmu/physmem.c
> > @@ -2163,38 +2163,8 @@ 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 *ram_block, ram_addr_t addr)
> > -{
> > -    RAMBlock *block = ram_block;
> > -
> > -    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.
> >   */
> > @@ -2202,7 +2172,9 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_block, ram_addr_t addr,
> >                                   hwaddr *size, bool lock)
> >  {
> >      RAMBlock *block = ram_block;
> > -    if (*size == 0) {
> > +    hwaddr len = 0;
> > +
> > +    if (size && *size == 0) {
> >          return NULL;
> >      }
> >  
> > @@ -2210,7 +2182,10 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_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
> > @@ -2218,7 +2193,7 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_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);
> > @@ -2227,6 +2202,19 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_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
> >