[SLOF] [PATCH v4] board-qemu: add private hcall to inform host on "phandle" update

[Alexey Kardashevskiy]

Thomas,

What is this business with phandle replacements all about? I looked at the
history which says "SLOF has a different concept of phandles" but it does
not say what would break if SLOF kept using phandles from QEMU.

I applied the chunk below and could not see any difference in how SLOF or a
guest kernel behave (slof can boot from virtio-net, guest can use mellanox
iov vfio-pci device):

diff --git a/board-qemu/slof/fdt.fs b/board-qemu/slof/fdt.fs
index a24e344..54a4bf8 100644
--- a/board-qemu/slof/fdt.fs
+++ b/board-qemu/slof/fdt.fs
@@ -449,4 +449,4 @@ r> drop
     fdt-cas-fix?
 ;

-s" /" find-node fdt-fix-phandles
+\ s" /" find-node fdt-fix-phandles


What am I missing here?


ps. the patch is correct assuming we still need the phandle replacement
trick :)


On 24/07/17 22:34, Greg Kurz wrote:
> The "interrupt-map" property in each PHB node references the "phandle"
> property of the "interrupt-controller" node. This is used by the guest
> OS to setup IRQs for any PCI device plugged into the PHB. QEMU sets this
> property to an arbitrary value in the flattened DT passed to SLOF.
> 
> Since commit 82954d4c1088, SLOF has some generic code to convert all
> references to any "phandle" property to a SLOF specific value.
> 
> This is is perfectly okay for coldplug devices, since the guest OS only
> sees the converted value in "interrupt-map". It is a problem though for
> hotplug devices. Since they don't go through SLOF, the guest OS receives
> the arbitrary value set by QEMU and fails to setup IRQs.
> 
> In order to support PHB hotplug, this patch introduces a new private
> hcall, which allows SLOF to tell QEMU that a "phandle" was converted
> from an old value to a new value.
> 
> Suggested-by: Thomas Huth <thuth at redhat.com>
> Signed-off-by: Greg Kurz <groug at kaod.org>
> ---
> v4: - fix bad stack usage in fdt-hv-update-phandle error path
> 
> v3: - drop "<> 0" before IF
> 
> v2: - use ?dup
>     - switch the order of the parameters of hv-update-phandle
>     - added stack comment to hv-update-phandle
> ---
>  board-qemu/slof/fdt.fs    |   14 ++++++++++++--
>  lib/libhvcall/hvcall.code |    7 +++++++
>  lib/libhvcall/hvcall.in   |    1 +
>  lib/libhvcall/libhvcall.h |    1 +
>  4 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/board-qemu/slof/fdt.fs b/board-qemu/slof/fdt.fs
> index 851645eae299..a24e3449e7c1 100644
> --- a/board-qemu/slof/fdt.fs
> +++ b/board-qemu/slof/fdt.fs
> @@ -308,18 +308,28 @@ fdt-claim-reserve
>     3drop
>  ;
>  
> +\ Tell QEMU about the updated phandle:
> +: fdt-hv-update-phandle ( old new -- )
> +   hv-update-phandle ?dup IF
> +      \ Ignore hcall not implemented error, print error otherwise
> +      dup -2 <> IF ." HV-UPDATE-PHANDLE error: " . cr ELSE drop THEN
> +   THEN
> +;
> +
>  \ Replace one FDT phandle "val" with a OF1275 phandle "node" in the
>  \ whole tree:
>  : fdt-update-phandle ( val node -- )
>     >r
>     FALSE TO (fdt-phandle-replaced)
> -   r@ s" /" find-node               ( val node root )
> -   fdt-replace-all-phandles
> +   r@ 2dup s" /" find-node          ( val node val node root )
> +   fdt-replace-all-phandles         ( val node )
>     (fdt-phandle-replaced) IF
> +      fdt-hv-update-phandle
>        r@ set-node
>        s" phandle" delete-property
>        s" linux,phandle" delete-property
>     ELSE
> +      2drop
>        diagnostic-mode? IF
>           cr ." Warning: Did not replace phandle in " r@ node>path type cr
>        THEN
> diff --git a/lib/libhvcall/hvcall.code b/lib/libhvcall/hvcall.code
> index 0ff50f27e8a9..834974862ef5 100644
> --- a/lib/libhvcall/hvcall.code
> +++ b/lib/libhvcall/hvcall.code
> @@ -129,3 +129,10 @@ PRIM(check_X2d_and_X2d_patch_X2d_sc1)
>  
>  	patch_broken_sc1((void*)start, (void*)end, (void*)patch_ins);
>  MIRP
> +
> +// : hv-update-phandle ( old_phandle new_phandle -- res )
> +PRIM(hv_X2d_update_X2d_phandle)
> +	uint32_t new_phandle = TOS.u; POP;
> +	uint32_t old_phandle = TOS.u;
> +	TOS.u = hv_generic(KVMPPC_H_UPDATE_PHANDLE, old_phandle, new_phandle);
> +MIRP
> diff --git a/lib/libhvcall/hvcall.in b/lib/libhvcall/hvcall.in
> index 4437b77f001d..ab7513af8977 100644
> --- a/lib/libhvcall/hvcall.in
> +++ b/lib/libhvcall/hvcall.in
> @@ -31,4 +31,5 @@ cod(RX!)
>  cod(hv-logical-memop)
>  cod(hv-cas)
>  cod(hv-rtas-update)
> +cod(hv-update-phandle)
>  cod(get-print-version)
> diff --git a/lib/libhvcall/libhvcall.h b/lib/libhvcall/libhvcall.h
> index b2ea3f6bf944..5776a2b772f7 100644
> --- a/lib/libhvcall/libhvcall.h
> +++ b/lib/libhvcall/libhvcall.h
> @@ -25,6 +25,7 @@
>  /* Client Architecture support */
>  #define KVMPPC_H_CAS            (KVMPPC_HCALL_BASE + 0x2)
>  #define KVMPPC_H_RTAS_UPDATE    (KVMPPC_HCALL_BASE + 0x3)
> +#define KVMPPC_H_UPDATE_PHANDLE (KVMPPC_HCALL_BASE + 0x4)
>  
>  #ifndef __ASSEMBLY__
>  
> 
> _______________________________________________
> SLOF mailing list
> SLOF at lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/slof
> 


-- 
Alexey