From: Greg Kurz <groug@kaod.org>
To: "Cédric Le Goater" <clg@kaod.org>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH] spapr/xive: skip partially initialized vCPUs in presenter
Date: Tue, 1 Oct 2019 13:06:14 +0200 [thread overview]
Message-ID: <20191001130614.226ef6a2@bahia.w3ibm.bluemix.net> (raw)
In-Reply-To: <20191001085722.32755-1-clg@kaod.org>
On Tue, 1 Oct 2019 10:57:22 +0200
Cédric Le Goater <clg@kaod.org> wrote:
> When vCPUs are hotplugged, they are added to the QEMU CPU list before
> being fully realized. This can crash the XIVE presenter because the
> 'tctx' pointer is not necessarily initialized when looking for a
> matching target.
>
Ouch... :-\
> These vCPUs are not valid targets for the presenter. Skip them.
>
This likely fixes this specific issue, but more generally, this
seems to indicate that using CPU_FOREACH() is rather fragile.
What about tracking XIVE TM contexts with a QLIST in xive.c ?
================================================================================
diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
index 6d38755f8459..89b9ef7f20b1 100644
--- a/include/hw/ppc/xive.h
+++ b/include/hw/ppc/xive.h
@@ -319,6 +319,8 @@ typedef struct XiveTCTX {
qemu_irq os_output;
uint8_t regs[XIVE_TM_RING_COUNT * XIVE_TM_RING_SIZE];
+
+ QTAILQ_ENTRY(XiveTCTX) next;
} XiveTCTX;
/*
diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index b7417210d817..f7721c711041 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -568,6 +568,8 @@ static void xive_tctx_reset(void *dev)
ipb_to_pipr(tctx->regs[TM_QW3_HV_PHYS + TM_IPB]);
}
+static QTAILQ_HEAD(, XiveTCTX) xive_tctx_list = QTAILQ_HEAD_INITIALIZER(xive_tctx_list);
+
static void xive_tctx_realize(DeviceState *dev, Error **errp)
{
XiveTCTX *tctx = XIVE_TCTX(dev);
@@ -609,10 +611,14 @@ static void xive_tctx_realize(DeviceState *dev, Error **errp)
}
qemu_register_reset(xive_tctx_reset, dev);
+ QTAILQ_INSERT_HEAD(&xive_tctx_list, tctx, next);
}
static void xive_tctx_unrealize(DeviceState *dev, Error **errp)
{
+ XiveTCTX *tctx = XIVE_TCTX(dev);
+
+ QTAILQ_REMOVE(&xive_tctx_list, tctx, next);
qemu_unregister_reset(xive_tctx_reset, dev);
}
@@ -1385,15 +1391,14 @@ static bool xive_presenter_match(XiveRouter *xrtr, uint8_t format,
bool cam_ignore, uint8_t priority,
uint32_t logic_serv, XiveTCTXMatch *match)
{
- CPUState *cs;
+ XiveTCTX *tctx;
/*
* TODO (PowerNV): handle chip_id overwrite of block field for
* hardwired CAM compares
*/
- CPU_FOREACH(cs) {
- XiveTCTX *tctx = xive_router_get_tctx(xrtr, cs);
+ QTAILQ_FOREACH(tctx, &xive_tctx_list, next) {
int ring;
/*
================================================================================
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
> hw/intc/xive.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index b7417210d817..29df06df1136 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -1396,6 +1396,14 @@ static bool xive_presenter_match(XiveRouter *xrtr, uint8_t format,
> XiveTCTX *tctx = xive_router_get_tctx(xrtr, cs);
> int ring;
>
> + /*
> + * Skip partially initialized vCPUs. This can happen when
> + * vCPUs are hotplugged.
> + */
> + if (!tctx) {
> + continue;
> + }
> +
> /*
> * HW checks that the CPU is enabled in the Physical Thread
> * Enable Register (PTER).
next prev parent reply other threads:[~2019-10-01 11:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-01 8:57 [PATCH] spapr/xive: skip partially initialized vCPUs in presenter Cédric Le Goater
2019-10-01 11:06 ` Greg Kurz [this message]
2019-10-01 11:56 ` Cédric Le Goater
2019-10-01 16:56 ` Greg Kurz
2019-10-02 1:02 ` David Gibson
2019-10-02 14:21 ` Greg Kurz
2019-10-02 14:47 ` Cédric Le Goater
2019-10-02 22:37 ` David Gibson
2019-10-03 8:02 ` Cédric Le Goater
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