On Fri, Oct 04, 2019 at 01:54:35PM +0200, Paolo Bonzini wrote:
> On 04/10/19 12:38, David Gibson wrote:
> > In order to call RTAS functions on powerpc kvm-unit-tests relies on the
> > RTAS blob supplied by qemu. But new versions of qemu don't supply an RTAS
> > blob: since the normal way for guests to get RTAS is to call the guest
> > firmware's instantiate-rtas function, we now rely on that guest firmware
> > to provide the RTAS code itself.
> >
> > But qemu-kvm-tests bypasses the usual guest firmware to just run itself,
> > so we can't get the rtas blob from SLOF.
> >
> > But.. in fact the RTAS blob under qemu is a bit of a sham anyway - it's
> > a tiny wrapper that forwards the RTAS call to a hypercall. So, we can
> > just invoke that hypercall directly.
> >
> > Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
>
> Would it be hard to call instantiate-rtas?
Fairly. First, we'd have to not use -bios to replace the normal SLOF
firmware - that could significantly slow down tests, since SLOF itself
takes a little while to start up. Then we'd need to get the unit
tests to boot out of slof which is a different interface from the raw
one we're using now. Then we'd need to get it to use the OF client
interface to call instantiate-rtas - we currently don't ever call OF
(obviously, since we don't even load it).
> I'm not sure if you have any
> interest in running kvm-unit-tests on hypervisors that might have a
> different way to process RTAS calls.
Probably not..?
>
> Paolo
>
> > ---
> > lib/powerpc/asm/hcall.h | 3 +++
> > lib/powerpc/rtas.c | 6 +++---
> > powerpc/cstart64.S | 20 ++++++++++++++++----
> > 3 files changed, 22 insertions(+), 7 deletions(-)
> >
> > So.. "new versions of qemu" in this case means ones that incorporate
> > the pull request I just sent today.
> >
> > diff --git a/lib/powerpc/asm/hcall.h b/lib/powerpc/asm/hcall.h
> > index a8bd7e3..1173fea 100644
> > --- a/lib/powerpc/asm/hcall.h
> > +++ b/lib/powerpc/asm/hcall.h
> > @@ -24,6 +24,9 @@
> > #define H_RANDOM 0x300
> > #define H_SET_MODE 0x31C
> >
> > +#define KVMPPC_HCALL_BASE 0xf000
> > +#define KVMPPC_H_RTAS (KVMPPC_HCALL_BASE + 0x0)
> > +
> > #ifndef __ASSEMBLY__
> > /*
> > * hcall_have_broken_sc1 checks if we're on a host with a broken sc1.
> > diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> > index 2e7e0da..41c0a24 100644
> > --- a/lib/powerpc/rtas.c
> > +++ b/lib/powerpc/rtas.c
> > @@ -46,9 +46,9 @@ void rtas_init(void)
> > prop = fdt_get_property(dt_fdt(), node,
> > "linux,rtas-entry", &len);
> > if (!prop) {
> > - printf("%s: /rtas/linux,rtas-entry: %s\n",
> > - __func__, fdt_strerror(len));
> > - abort();
> > + /* We don't have a qemu provided RTAS blob, enter_rtas
> > + * will use H_RTAS directly */
> > + return;
> > }
> > data = (u32 *)prop->data;
> > rtas_entry = (unsigned long)fdt32_to_cpu(*data);
> > diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
> > index ec673b3..972851f 100644
> > --- a/powerpc/cstart64.S
> > +++ b/powerpc/cstart64.S
> > @@ -121,13 +121,25 @@ halt:
> >
> > .globl enter_rtas
> > enter_rtas:
> > + LOAD_REG_ADDR(r11, rtas_entry)
> > + ld r10, 0(r11)
> > +
> > + cmpdi r10,0
> > + bne external_rtas
> > +
> > + /* Use H_RTAS directly */
> > + mr r4,r3
> > + lis r3,KVMPPC_H_RTAS@h
> > + ori r3,r3,KVMPPC_H_RTAS@l
> > + b hcall
> > +
> > +external_rtas:
> > + /* Use external RTAS blob */
> > mflr r0
> > std r0, 16(r1)
> >
> > - LOAD_REG_ADDR(r10, rtas_return_loc)
> > - mtlr r10
> > - LOAD_REG_ADDR(r11, rtas_entry)
> > - ld r10, 0(r11)
> > + LOAD_REG_ADDR(r11, rtas_return_loc)
> > + mtlr r11
> >
> > mfmsr r11
> > LOAD_REG_IMMEDIATE(r9, RTAS_MSR_MASK)
> >
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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