[XEN PATCH] hvmloader: Fix reading ACPI PM1 CNT value

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

In order to get the CNT value from QEMU, we were supposed to read a
word, according to the implementation in QEMU. But it has been lax and
allowed to read a single byte. This has changed with commit
5d971f9e6725 ("memory: Revert "memory: accept mismatching sizes in
memory_region_access_valid"") and result in hvmloader crashing on
the BUG_ON.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

---

I'll try to have the QEMU implementation changes to allow reading a
byte, but it would probably by nice to not have to change qemu.
---
 tools/firmware/hvmloader/hvmloader.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/firmware/hvmloader/hvmloader.c 
b/tools/firmware/hvmloader/hvmloader.c
index 598a22627872..bdcbe4a26664 100644
--- a/tools/firmware/hvmloader/hvmloader.c
+++ b/tools/firmware/hvmloader/hvmloader.c
@@ -256,7 +256,7 @@ static const struct bios_config *detect_bios(void)
 
 static void acpi_enable_sci(void)
 {
-    uint8_t pm1a_cnt_val;
+    uint16_t pm1a_cnt_val;
 
 #define PIIX4_SMI_CMD_IOPORT 0xb2
 #define PIIX4_ACPI_ENABLE    0xf1
@@ -265,11 +265,11 @@ static void acpi_enable_sci(void)
      * PIIX4 emulation in QEMU has SCI_EN=0 by default. We have no legacy
      * SMM implementation, so give ACPI control to the OSPM immediately.
      */
-    pm1a_cnt_val = inb(ACPI_PM1A_CNT_BLK_ADDRESS_V1);
+    pm1a_cnt_val = inw(ACPI_PM1A_CNT_BLK_ADDRESS_V1);
     if ( !(pm1a_cnt_val & ACPI_PM1C_SCI_EN) )
         outb(PIIX4_SMI_CMD_IOPORT, PIIX4_ACPI_ENABLE);
 
-    pm1a_cnt_val = inb(ACPI_PM1A_CNT_BLK_ADDRESS_V1);
+    pm1a_cnt_val = inw(ACPI_PM1A_CNT_BLK_ADDRESS_V1);
     BUG_ON(!(pm1a_cnt_val & ACPI_PM1C_SCI_EN));
 }
 
-- 
Anthony PERARD