On Tue, 27 Feb 2024, Vikram Garhwal wrote:
> From: Juergen Gross <jgr...@suse.com>
>
> In order to support mapping and unmapping guest memory dynamically to
> and from qemu during address_space_[un]map() operations add the map()
> and unmap() callbacks to MemoryRegionOps.
>
> Those will be used e.g. for Xen grant mappings when performing guest
> I/Os.
>
> Signed-off-by: Juergen Gross <jgr...@suse.com>
> Signed-off-by: Vikram Garhwal <vikram.garh...@amd.com>
Reviewed-by: Stefano Stabellini <sstabell...@kernel.org>
> ---
> include/exec/memory.h | 21 ++++++++++++++++++
> system/physmem.c | 50 +++++++++++++++++++++++++++++++++----------
> 2 files changed, 60 insertions(+), 11 deletions(-)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 8626a355b3..9f7dfe59c7 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -282,6 +282,27 @@ struct MemoryRegionOps {
> unsigned size,
> MemTxAttrs attrs);
>
> + /*
> + * Dynamically create mapping. @addr is the guest address to map; @plen
> + * is the pointer to the usable length of the buffer.
> + * @mr contents can be changed in case a new memory region is created for
> + * the mapping.
> + * Returns the buffer address for accessing the data.
> + */
> + void *(*map)(MemoryRegion **mr,
> + hwaddr addr,
> + hwaddr *plen,
> + bool is_write,
> + MemTxAttrs attrs);
> +
> + /* Unmap an area obtained via map() before. */
> + void (*unmap)(MemoryRegion *mr,
> + void *buffer,
> + ram_addr_t addr,
> + hwaddr len,
> + bool is_write,
> + hwaddr access_len);
> +
> enum device_endian endianness;
> /* Guest-visible constraints: */
> struct {
> diff --git a/system/physmem.c b/system/physmem.c
> index 949dcb20ba..d989e9fc1f 100644
> --- a/system/physmem.c
> +++ b/system/physmem.c
> @@ -3141,6 +3141,7 @@ void *address_space_map(AddressSpace *as,
> hwaddr len = *plen;
> hwaddr l, xlat;
> MemoryRegion *mr;
> + void *ptr = NULL;
> FlatView *fv;
>
> if (len == 0) {
> @@ -3174,12 +3175,20 @@ void *address_space_map(AddressSpace *as,
> return bounce.buffer;
> }
>
> -
> memory_region_ref(mr);
> +
> + if (mr->ops && mr->ops->map) {
> + ptr = mr->ops->map(&mr, addr, plen, is_write, attrs);
> + }
> +
> *plen = flatview_extend_translation(fv, addr, len, mr, xlat,
> l, is_write, attrs);
> fuzz_dma_read_cb(addr, *plen, mr);
> - return qemu_ram_ptr_length(mr->ram_block, xlat, plen, true);
> + if (ptr == NULL) {
> + ptr = qemu_ram_ptr_length(mr->ram_block, xlat, plen, true);
> + }
> +
> + return ptr;
> }
>
> /* Unmaps a memory region previously mapped by address_space_map().
> @@ -3195,11 +3204,16 @@ void address_space_unmap(AddressSpace *as, void
> *buffer, hwaddr len,
>
> mr = memory_region_from_host(buffer, &addr1);
> assert(mr != NULL);
> - if (is_write) {
> - invalidate_and_set_dirty(mr, addr1, access_len);
> - }
> - if (xen_enabled()) {
> - xen_invalidate_map_cache_entry(buffer);
> +
> + if (mr->ops && mr->ops->unmap) {
> + mr->ops->unmap(mr, buffer, addr1, len, is_write, access_len);
> + } else {
> + if (is_write) {
> + invalidate_and_set_dirty(mr, addr1, access_len);
> + }
> + if (xen_enabled()) {
> + xen_invalidate_map_cache_entry(buffer);
> + }
> }
> memory_region_unref(mr);
> return;
> @@ -3272,10 +3286,18 @@ int64_t address_space_cache_init(MemoryRegionCache
> *cache,
> * doing this if we found actual RAM, which behaves the same
> * regardless of attributes; so UNSPECIFIED is fine.
> */
> + if (mr->ops && mr->ops->map) {
> + cache->ptr = mr->ops->map(&mr, addr, &l, is_write,
> + MEMTXATTRS_UNSPECIFIED);
> + }
> +
> l = flatview_extend_translation(cache->fv, addr, len, mr,
> cache->xlat, l, is_write,
> MEMTXATTRS_UNSPECIFIED);
> - cache->ptr = qemu_ram_ptr_length(mr->ram_block, cache->xlat, &l,
> true);
> + if (!cache->ptr) {
> + cache->ptr = qemu_ram_ptr_length(mr->ram_block, cache->xlat, &l,
> + true);
> + }
> } else {
> cache->ptr = NULL;
> }
> @@ -3297,14 +3319,20 @@ void address_space_cache_invalidate(MemoryRegionCache
> *cache,
>
> void address_space_cache_destroy(MemoryRegionCache *cache)
> {
> - if (!cache->mrs.mr) {
> + MemoryRegion *mr = cache->mrs.mr;
> +
> + if (!mr) {
> return;
> }
>
> - if (xen_enabled()) {
> + if (mr->ops && mr->ops->unmap) {
> + mr->ops->unmap(mr, cache->ptr, cache->xlat, cache->len,
> + cache->is_write, cache->len);
> + } else if (xen_enabled()) {
> xen_invalidate_map_cache_entry(cache->ptr);
> }
> - memory_region_unref(cache->mrs.mr);
> +
> + memory_region_unref(mr);
> flatview_unref(cache->fv);
> cache->mrs.mr = NULL;
> cache->fv = NULL;
> --
> 2.17.1
>
