Re: [Qemu-devel] [PATCH] hw/isa/lpc_ich9: inject the SMI on the VCPU that is writing to APM_CNT

[Kevin O'Connor <kevin@koconnor.net>]

On Thu, Oct 22, 2015 at 10:40:08AM +0200, Paolo Bonzini wrote:
> On 21/10/2015 20:36, Jordan Justen wrote:
> > On 2015-10-20 11:14:00, Laszlo Ersek wrote:
> > > Commit 4d00636e97b7 ("ich9: Add the lpc chip", Nov 14 2012) added the
> > > ich9_apm_ctrl_changed() ioport write callback function such that it would
> > > inject the SMI, in response to a write to the APM_CNT register, on the
> > > first CPU, invariably.
> > > 
> > > Since this register is used by guest code to trigger an SMI synchronously,
> > > the interrupt should be injected on the VCPU that is performing the write.
> > 
> > Why not send an SMI to *all* processors, like the real chipsets do?
> 
> That's much less scalable, and more important I would have to check that
> SeaBIOS can handle that correctly.  It probably doesn't, as it doesn't
> relocate SMBASEs.

SeaBIOS is only expecting its SMI handler to be called once in
response to a synchronous SMI.  We can change SeaBIOS to fix that.

SeaBIOS does relocate the smbase from 0x30000 to 0xa0000 during its
init phase (by creating a synchronous SMI on the BSP and then setting
the smbase register to 0xa0000 in the smi handler).

-Kevin