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

Re: [PATCH] arm/its: enable LPIs before mapping the collection table



Hi Rahul,

On 27/04/2022 17:14, Rahul Singh wrote:
MAPC_LPI_OFF ITS command error can be reported to software if LPIs are
not enabled before mapping the collection table using MAPC command.

Enable the LPIs using GICR_CTLR.EnableLPIs before mapping the collection
table.

Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
---
  xen/arch/arm/gic-v3.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 3c472ed768..8fb0014b16 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -812,11 +812,11 @@ static int gicv3_cpu_init(void)
      /* If the host has any ITSes, enable LPIs now. */
      if ( gicv3_its_host_has_its() )
      {
+        if ( !gicv3_enable_lpis() )
+            return -EBUSY;

gicv3_enable_lpis() is using writel_relaxed(). So in theory, the write may not be visible before gicv3_its_setup_collection() send the command.

So I think we need to add an smp_wmb() to ensure the ordering with a comment explaning why this is necessary.

Cheers,

--
Julien Grall



 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.