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Re: [RFC PATCH-for-9.0 v2 13/19] hw/xen: Remove use of 'target_ulong' in


From: Philippe Mathieu-Daudé
Subject: Re: [RFC PATCH-for-9.0 v2 13/19] hw/xen: Remove use of 'target_ulong' in handle_ioreq()
Date: Wed, 6 Mar 2024 18:16:29 +0100
User-agent: Mozilla Thunderbird

Cc'ing Anton.

On 14/11/23 15:38, Philippe Mathieu-Daudé wrote:
Per commit f17068c1c7 ("xen-hvm: reorganize xen-hvm and move common
function to xen-hvm-common"), handle_ioreq() is expected to be
target-agnostic. However it uses 'target_ulong', which is a target
specific definition.

Per xen/include/public/hvm/ioreq.h header:

   struct ioreq {
     uint64_t addr;          /* physical address */
     uint64_t data;          /* data (or paddr of data) */
     uint32_t count;         /* for rep prefixes */
     uint32_t size;          /* size in bytes */
     uint32_t vp_eport;      /* evtchn for notifications to/from device model */
     uint16_t _pad0;
     uint8_t state:4;
     uint8_t data_is_ptr:1;  /* if 1, data above is the guest paddr
                              * of the real data to use. */
     uint8_t dir:1;          /* 1=read, 0=write */
     uint8_t df:1;
     uint8_t _pad1:1;
     uint8_t type;           /* I/O type */
   };
   typedef struct ioreq ioreq_t;

If 'data' is not a pointer, it is a u64.

- In PIO / VMWARE_PORT modes, only 32-bit are used.

- In MMIO COPY mode, memory is accessed by chunks of 64-bit

- In PCI_CONFIG mode, access is u8 or u16 or u32.

- None of TIMEOFFSET / INVALIDATE use 'req'.

- Fallback is only used in x86 for VMWARE_PORT.

Masking the upper bits of 'data' to keep 'req->size' low bits
is irrelevant of the target word size. Remove the word size
check and always extract the relevant bits.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
  hw/xen/xen-hvm-common.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/xen/xen-hvm-common.c b/hw/xen/xen-hvm-common.c
index bb3cfb200c..fb81bd8fbc 100644
--- a/hw/xen/xen-hvm-common.c
+++ b/hw/xen/xen-hvm-common.c
@@ -1,5 +1,6 @@
  #include "qemu/osdep.h"
  #include "qemu/units.h"
+#include "qemu/bitops.h"
  #include "qapi/error.h"
  #include "trace.h"
@@ -426,9 +427,8 @@ static void handle_ioreq(XenIOState *state, ioreq_t *req)
      trace_handle_ioreq(req, req->type, req->dir, req->df, req->data_is_ptr,
                         req->addr, req->data, req->count, req->size);
- if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) &&
-            (req->size < sizeof (target_ulong))) {
-        req->data &= ((target_ulong) 1 << (8 * req->size)) - 1;
+    if (!req->data_is_ptr && (req->dir == IOREQ_WRITE)) {
+        req->data = extract64(req->data, 0, BITS_PER_BYTE * req->size);
      }
if (req->dir == IOREQ_WRITE)




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