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Re: [Xen-devel] [PATCH] Avoid cpu_physical_memory_rw() with a constant is_write argument

On 2/18/20 7:49 PM, Peter Maydell wrote:
On Tue, 18 Feb 2020 at 17:57, Stefan Weil <sw@xxxxxxxxxxx> wrote:

Am 18.02.20 um 14:20 schrieb Philippe Mathieu-Daudé:

This commit was produced with the included Coccinelle script

Inspired-by: Peter Maydell <peter.maydell@xxxxxxxxxx>
Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
Based-on: <20200218112457.22712-1-peter.maydell@xxxxxxxxxx>
diff --git a/target/i386/hax-all.c b/target/i386/hax-all.c
index a8b6e5aeb8..f5971ccc74 100644
--- a/target/i386/hax-all.c
+++ b/target/i386/hax-all.c
@@ -376,8 +376,8 @@ static int hax_handle_fastmmio(CPUArchState *env, struct 
hax_fastmmio *hft)
           *  hft->direction == 2: gpa ==> gpa2
          uint64_t value;
-        cpu_physical_memory_rw(hft->gpa, (uint8_t *) &value, hft->size, 0);
-        cpu_physical_memory_rw(hft->gpa2, (uint8_t *) &value, hft->size, 1);
+        cpu_physical_memory_read(hft->gpa, (uint8_t *)&value, hft->size);
+        cpu_physical_memory_write(hft->gpa2, (uint8_t *)&value, hft->size);

Maybe those type casts could be removed, too. They are no longer needed
after your modification.

I think that we should fix the inconsistency where these functions
all take "uint8_t* buf":

  - address_space_rw()
  - address_space_read()
  - address_space_write()
  - address_space_write_rom()
  - cpu_physical_memory_rw()
  - cpu_memory_rw_debug()

but these take void*:
  - cpu_physical_memory_read()
  - cpu_physical_memory_write()
  - address_space_write_cached()
  - address_space_read_cached_slow()
  - address_space_write_cached_slow()
  - pci_dma_read()
  - pci_dma_write()
  - pci_dma_rw()
  - dma_memory_read()
  - dma_memory_write()
  - dma_memory_rw()
  - dma_memory_rw_relaxed()

I don't understand well cpu_physical_memory*(). Aren't these obsolete?
They confuse me when using multi-core CPUs.

Depending on which way we go we would either want to remove these
casts, or not.

I guess that we have more cases of 'void*', and that would
certainly be the easier way to convert (otherwise we probably
need to add a bunch of new casts to uint8_t* in various callsites),
but I don't have a strong opinion. Paolo ?

I thought about it too but it is quite some work, and I'v to admit I lost some faith with my previous chardev conversion. There Paolo/Daniel agreed to follow the libc read()/write() prototypes.

-- PMM

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