Re: [Qemu-devel] [PATCH] fix acpi regression

[Isaku Yamahata <yamahata@valinux.co.jp>]

On Tue, Apr 12, 2011 at 05:08:18PM +0800, Wen Congyang wrote:
> At 04/12/2011 04:48 PM, Isaku Yamahata Write:
> > On Tue, Apr 12, 2011 at 01:13:15PM +0800, Wen Congyang wrote:
> >> This bug is introduced by commit 23910d3f.
> > 
> > Oh, Thanks. Good catch. I agree with the first hunk.
> > But what is the second hunk for? The GPE STS register is W1C.
> > (NULL check and 0xff masking is okay. it's a bit redundant, though)
> 
> I found this bug when I hotplug a nic.
> I do not know about ACPI.
> The second hunk is the same before commit 23910d3f.
> I will read ACPI spec to confirm it and update this patch.

You mean gpe_writeb(), gpe_write_val(), gpe_reset_val()?
gpe_reset_val() does W1C.
The GPE0_LEN of piix4 is 4 byte length and the first 2 registers are
sts register. From the old code,

static void gpe_reset_val(uint16_t *cur, int addr, uint32_t val)
{   
    uint16_t x1, x0 = val & 0xff;
    int shift = (addr & 1) ? 8 : 0;

    x1 = (*cur >> shift) & 0xff;

    x1 = x1 & ~x0; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< W1C

    *cur = (*cur & (0xff << (8 - shift))) | (x1 << shift);
}


static void gpe_writeb(void *opaque, uint32_t addr, uint32_t val)
{   
    PIIX4PMState *s = opaque;
    struct gpe_regs *g = &s->gpe;

    switch (addr) {
        case GPE_BASE:
        case GPE_BASE + 1:
            gpe_reset_val(&g->sts, addr, val);
            break;

thanks,

> 
> Thanks
> 
> > 
> >>From ACPI4 spec 4.7.4.1.1.
> > can only be cleared by software writing a "1" to its respective bit position.
> > 
> > thanks,
> > 
> >>
> >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> >>
> >> ---
> >>  hw/acpi.c |   10 +++-------
> >>  1 files changed, 3 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/hw/acpi.c b/hw/acpi.c
> >> index e372474..790bd3b 100644
> >> --- a/hw/acpi.c
> >> +++ b/hw/acpi.c
> >> @@ -355,7 +355,7 @@ static uint8_t *acpi_gpe_ioport_get_ptr(ACPIGPE *gpe, uint32_t addr)
> >>      if (addr < gpe->len / 2) {
> >>          cur = gpe->sts + addr;
> >>      } else if (addr < gpe->len) {
> >> -        cur = gpe->en + addr;
> >> +        cur = gpe->en + addr - gpe->len / 2;
> >>      } else {
> >>          abort();
> >>      }
> >> @@ -369,12 +369,8 @@ void acpi_gpe_ioport_writeb(ACPIGPE *gpe, uint32_t addr, uint32_t val)
> >>  
> >>      addr -= gpe->blk;
> >>      cur = acpi_gpe_ioport_get_ptr(gpe, addr);
> >> -    if (addr < gpe->len / 2) {
> >> -        /* GPE_STS */
> >> -        *cur = (*cur) & ~val;
> >> -    } else if (addr < gpe->len) {
> >> -        /* GPE_EN */
> >> -        *cur = val;
> >> +    if (cur != NULL) {
> >> +        *cur = val & 0xff;
> >>      } else {
> >>          abort();
> >>      }
> >> -- 
> >> 1.7.1
> >>
> 
> 

-- 
yamahata