Re: [Xen-devel] [PATCH 3/4] rombios interface for HVM S3

[Juergen Keil <jk@xxxxxxxx>]

Keir Fraser wrote:

> On 2/6/08 14:45, "Juergen Keil" <jk@xxxxxxxx> wrote:
> 
> > For unknown reasons, HVM S3 resume hangs in the bios when trying to load
> > the x_firmware_waking_vector from absolute address 0xEA01C (it hangs for
> > access to address 0x10000, but doesn't hang for 0xfffe).
> 
> It works on Intel because there we emulate the rombios, and our emulator
> does not bother with segment limit checks in real mode. This is actually
> more lenient than real hardware, hence an AMD CPU (which is directly
> executing the rombios code) will fault on the access because it is at a
> segment offset greater than 64kB.
> 
> Your patch is good. Please re-submit with a fixed changeset comment and a
> signed-off-by line. I'll then check it in.

Ok, comment is updated, see the attachment.

HVM S3 resume hangs in bios on AMD cpus; support 20-bit firmware_waking_vector

On AMD cpus, HVM S3 resume was hanging in the bios when trying
to load the x_firmware_waking_vector from absolute
address 0xEA01C (that is, a segment offset greater than 64kB).

This change now uses 20-bits (instead of 16) from the FACS
standard firmware_waking_vector.

Signed-off-by: Juergen keil <jk@xxxxxxxx>

diff --git a/tools/firmware/rombios/rombios.c b/tools/firmware/rombios/rombios.c
--- a/tools/firmware/rombios/rombios.c
+++ b/tools/firmware/rombios/rombios.c
@@ -2311,10 +2311,31 @@
 #define ACPI_FACS_OFFSET 0x10
 /* S3 resume status in CMOS 0Fh shutdown status byte*/
 
+Bit32u facs_get32(offs)
+Bit16u offs;
+{
+ASM_START
+  push bp
+  mov  bp, sp
+
+    push ds
+    mov ax, #(ACPI_FACS_ADDRESS >> 4)
+    mov ds, ax
+
+    mov bx, 4[bp]
+    mov ax, [bx]
+    mov dx, 2[bx]
+    pop ds
+
+  pop  bp
+ASM_END
+}
+
+
 void 
 s3_resume()
 {
-    Bit16u s3_wakeup_vector;
+    Bit32u s3_wakeup_vector;
     extern Bit16u s3_wakeup_ip;
     extern Bit16u s3_wakeup_cs;
     extern Bit8u s3_resume_flag;
@@ -2330,19 +2351,14 @@
     }
     s3_resume_flag = 0;
 
-ASM_START
-    mov ax, #0x0
-    mov ds, ax
-ASM_END
-
     /* get x_firmware_waking_vector */
-    s3_wakeup_vector = *((Bit16u*)(ACPI_FACS_ADDRESS+ACPI_FACS_OFFSET+24));
-    if (s3_wakeup_vector == 0){
+    s3_wakeup_vector = facs_get32(ACPI_FACS_OFFSET+24);
+    if (!s3_wakeup_vector) {
         /* get firmware_waking_vector */
-        s3_wakeup_vector = *((Bit16u*)(ACPI_FACS_ADDRESS+ACPI_FACS_OFFSET+12));
-        if (s3_wakeup_vector == 0){
+       s3_wakeup_vector = facs_get32(ACPI_FACS_OFFSET+12);
+       if (!s3_wakeup_vector) {
             goto s3_out;
-        }
+       }
     }
 
     /* setup wakeup vector */
@@ -2350,13 +2366,6 @@
     s3_wakeup_cs = s3_wakeup_vector >> 4;
 
 ASM_START
-    mov bx, [_s3_wakeup_cs]
-    mov dx, [_s3_wakeup_ip]
-
-    mov ax, #0xF000
-    mov ds, ax
-    mov [_s3_wakeup_cs], bx
-    mov [_s3_wakeup_ip], dx
     jmpf [_s3_wakeup_ip]
 
 ; S3 data

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