[Qemu-devel] [PATCH] msix: allow byte and word reading from mmio

[Bernhard Kohl <bernhard.kohl@nsn.com>]

It's legal that the guest reads a single byte or word from mmio.
I have an OS which reads single bytes and it works fine on real
hardware. Maybe this happens due to casting.

Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>
---
  hw/msix.c |   20 ++++++++++++++++----
  1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/hw/msix.c b/hw/msix.c
index d99403a..7dac7f7 100644
--- a/hw/msix.c
+++ b/hw/msix.c
@@ -100,10 +100,22 @@ static uint32_t msix_mmio_readl(void *opaque, 
target_phys_addr_t addr)
      return pci_get_long(page + offset);
  }

-static uint32_t msix_mmio_read_unallowed(void *opaque, 
target_phys_addr_t addr)
+static uint32_t msix_mmio_readw(void *opaque, target_phys_addr_t addr)
  {
-    fprintf(stderr, "MSI-X: only dword read is allowed!\n");
-    return 0;
+    PCIDevice *dev = opaque;
+    unsigned int offset = addr & (MSIX_PAGE_SIZE - 1) & ~0x1;
+    void *page = dev->msix_table_page;
+
+    return pci_get_word(page + offset);
+}
+
+static uint32_t msix_mmio_readb(void *opaque, target_phys_addr_t addr)
+{
+    PCIDevice *dev = opaque;
+    unsigned int offset = addr & (MSIX_PAGE_SIZE - 1);
+    void *page = dev->msix_table_page;
+
+    return pci_get_byte(page + offset);
  }

  static uint8_t msix_pending_mask(int vector)
@@ -198,7 +210,7 @@ static CPUWriteMemoryFunc * const msix_mmio_write[] = {
  };

  static CPUReadMemoryFunc * const msix_mmio_read[] = {
-    msix_mmio_read_unallowed, msix_mmio_read_unallowed, msix_mmio_readl
+    msix_mmio_readb, msix_mmio_readw, msix_mmio_readl
  };

  /* Should be called from device's map method. */
-- 
1.7.2