[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH] spapr/xive: Use xive_source_esb_len()

From: Gustavo Romero
Subject: Re: [PATCH] spapr/xive: Use xive_source_esb_len()
Date: Thu, 13 Aug 2020 20:01:54 -0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0

On 8/13/20 7:00 PM, Greg Kurz wrote:
On Thu, 13 Aug 2020 17:38:59 -0300
Gustavo Romero <gromero@linux.vnet.ibm.com> wrote:

Hi Greg,

Hi Gustavo,

On 8/13/20 2:28 PM, Greg Kurz wrote:
static inline size_t xive_source_esb_len(XiveSource *xsrc)
      return (1ull << xsrc->esb_shift) * xsrc->nr_irqs;

Signed-off-by: Greg Kurz <groug@kaod.org>
Follow-up on "ppc/xive: Rework setup of XiveSource::esb_mmio"
   hw/intc/spapr_xive.c     |    2 +-
   hw/intc/spapr_xive_kvm.c |    2 +-
   2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index 3c84f64dc464..4bd0d606ba17 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -336,7 +336,7 @@ static void spapr_xive_realize(DeviceState *dev, Error 
       sysbus_init_mmio(SYS_BUS_DEVICE(xive), &end_xsrc->esb_mmio);
/* Set the mapping address of the END ESB pages after the source ESBs */
-    xive->end_base = xive->vc_base + (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
+    xive->end_base = xive->vc_base + xive_source_esb_len(xsrc);
        * Allocate the routing tables
diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index 82a6f99f022d..3263b982239a 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -831,7 +831,7 @@ void kvmppc_xive_disconnect(SpaprInterruptController *intc)
/* Clear the KVM mapping */
       xsrc = &xive->source;
-    esb_len = (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
+    esb_len = xive_source_esb_len(xsrc);

hrm I'd like to not add another level of indirection here.
In this specific case I think it's more clear to read just

1ull << xsrc->esb_shift) * xsrc->nr_irqs

and get the idea of one IRQ per ESB page (or pair of pages,
for trigger and management), than one having to look at
what is inside "a box" called xive_source_esb_len().

Wrapping it under another function doesn't help more when
reading the code, XIVE is already tricky enough :)

Heh, XIVE is tricky enough that only a few people will dare
to touch this code and they'd better already know about the
one IRQ per ESB page thingy ;-)

Yea, maybe someday we get a cool documentation on it.

Luckily I came after Benh and Cédric and took some good info from
OPAL and QEMU code. I found out recently that XIVE support was
merged into FreeBSD and with that it also came some good comments
about xive...

More seriously, this is a matter of taste, but since you're likely
to be involved in XIVE a bit more than me, I'm perfectly fine with
keeping this open-coded.

Thanks, Greg.

Hope there is still some time to enjoy the summer over there :)


reply via email to

[Prev in Thread] Current Thread [Next in Thread]