> -----Original Message-----
> From: qemu-devel-bounces+yu.liu=freescale.com@xxxxxxxxxx
> [mailto:qemu-devel-bounces+yu.liu=freescale.com@xxxxxxxxxx]
> On Behalf Of stefano.stabellini@xxxxxxxxxxxxx
> Sent: Friday, May 20, 2011 1:36 AM
> To: qemu-devel@xxxxxxxxxx
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; agraf@xxxxxxx; Stefano Stabellini
> Subject: [Qemu-devel] [PATCH v2 4/5] exec.c: refactor
> cpu_physical_memory_map
>
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> Introduce qemu_ram_ptr_length that takes an address and a size as
> parameters rather than just an address.
>
> Refactor cpu_physical_memory_map so that we call
> qemu_ram_ptr_length only
> once rather than calling qemu_get_ram_ptr one time per page.
> This is not only more efficient but also tries to simplify
> the logic of
> the function.
> Currently we are relying on the fact that all the pages are mapped
> contiguously in qemu's address space: we have a check to make
> sure that
> the virtual address returned by qemu_get_ram_ptr from the
> second call on
> is consecutive. Now we are making this more explicit replacing all the
> calls to qemu_get_ram_ptr with a single call to qemu_ram_ptr_length
> passing a size argument.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> CC: agraf@xxxxxxx
> CC: anthony@xxxxxxxxxxxxx
> ---
> cpu-common.h | 1 +
> exec.c | 51
> ++++++++++++++++++++++++++++++++++-----------------
> 2 files changed, 35 insertions(+), 17 deletions(-)
>
> diff --git a/cpu-common.h b/cpu-common.h
> index 151c32c..085aacb 100644
> --- a/cpu-common.h
> +++ b/cpu-common.h
> @@ -64,6 +64,7 @@ void qemu_ram_free(ram_addr_t addr);
> void qemu_ram_remap(ram_addr_t addr, ram_addr_t length);
> /* This should only be used for ram local to a device. */
> void *qemu_get_ram_ptr(ram_addr_t addr);
> +void *qemu_ram_ptr_length(target_phys_addr_t addr,
> target_phys_addr_t *size);
> /* Same but slower, to use for migration, where the order of
> * RAMBlocks must not change. */
> void *qemu_safe_ram_ptr(ram_addr_t addr);
> diff --git a/exec.c b/exec.c
> index 21f21f0..ff9c174 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3111,6 +3111,31 @@ void *qemu_safe_ram_ptr(ram_addr_t addr)
> return NULL;
> }
>
> +/* Return a host pointer to guest's ram. Similar to qemu_get_ram_ptr
> + * but takes a size argument */
> +void *qemu_ram_ptr_length(target_phys_addr_t addr,
> target_phys_addr_t *size)
> +{
> + if (xen_mapcache_enabled())
> + return qemu_map_cache(addr, *size, 1);
> + else {
> + RAMBlock *block;
> +
> + QLIST_FOREACH(block, &ram_list.blocks, next) {
> + if (addr - block->offset < block->length) {
> + if (addr - block->offset + *size > block->length)
> + *size = block->length - addr + block->offset;
> + return block->host + (addr - block->offset);
> + }
> + }
> +
> + fprintf(stderr, "Bad ram offset %" PRIx64 "\n",
> (uint64_t)addr);
> + abort();
> +
> + *size = 0;
> + return NULL;
> + }
> +}
> +
> void qemu_put_ram_ptr(void *addr)
> {
> trace_qemu_put_ram_ptr(addr);
> @@ -3972,14 +3997,12 @@ void
> *cpu_physical_memory_map(target_phys_addr_t addr,
> int is_write)
> {
> target_phys_addr_t len = *plen;
> - target_phys_addr_t done = 0;
> + target_phys_addr_t todo = 0;
> int l;
> - uint8_t *ret = NULL;
> - uint8_t *ptr;
> target_phys_addr_t page;
> unsigned long pd;
> PhysPageDesc *p;
> - unsigned long addr1;
> + target_phys_addr_t addr1 = addr;
>
> while (len > 0) {
> page = addr & TARGET_PAGE_MASK;
> @@ -3994,7 +4017,7 @@ void
> *cpu_physical_memory_map(target_phys_addr_t addr,
> }
>
> if ((pd & ~TARGET_PAGE_MASK) != IO_MEM_RAM) {
> - if (done || bounce.buffer) {
> + if (todo || bounce.buffer) {
> break;
> }
> bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE,
> TARGET_PAGE_SIZE);
> @@ -4003,23 +4026,17 @@ void
> *cpu_physical_memory_map(target_phys_addr_t addr,
> if (!is_write) {
> cpu_physical_memory_read(addr, bounce.buffer, l);
> }
> - ptr = bounce.buffer;
> - } else {
> - addr1 = (pd & TARGET_PAGE_MASK) + (addr &
> ~TARGET_PAGE_MASK);
> - ptr = qemu_get_ram_ptr(addr1);
> - }
> - if (!done) {
> - ret = ptr;
> - } else if (ret + done != ptr) {
> - break;
> +
> + *plen = l;
> + return bounce.buffer;
> }
>
> len -= l;
> addr += l;
> - done += l;
> + todo += l;
> }
> - *plen = done;
> - return ret;
> + *plen = todo;
> + return qemu_ram_ptr_length(addr1, plen);
> }
>
> /* Unmaps a memory region previously mapped by
> cpu_physical_memory_map().
> --
> 1.7.2.3
Hello Stefano,
This commit breaks the case that guest memory doesn't start from 0.
In previous code
addr1 = (pd & TARGET_PAGE_MASK) + (addr & ~TARGET_PAGE_MASK);
This transfer guest physical addr to qemu ram_addr, and so that it can pass the
ram range checking.
But current code
addr1 = addr
this make it fail to pass the ram range checking.
Thanks,
Yu
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home