Hi,
On 19/09/2023 14:10, Julien Grall wrote:
On 19/09/2023 12:28, Volodymyr Babchuk wrote:
ITS manages Device Tables and Interrupt Translation Tables on its own,
so generally we are not interested which shareability and cacheability
attributes it uses. But there is one exception: ITS requires that DT
and ITT must be initialized with zeroes. If ITS belongs to the Inner
Cacheability domain there is no problem at all.
But in all other cases we need to do clean CPU caches manually, or
otherwise CPU can overwrite DT and ITT entries. From user perspective
this looks like interrupts are not delivered from a device.
Also, we will rename HOST_ITS_FLUSH_CMD_QUEUE flag to
HOST_ITS_FLUSH_BUFFERS because now this flag controls not only command
queue.
Reading the specification, CBASER will indicate the cacheability for the
command queue. But I couldn't find any reference saying this will apply
to the ITT as well.
If such reference doesn't exist then...
Signed-off-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
---
xen/arch/arm/gic-v3-its.c | 7 +++++--
xen/arch/arm/include/asm/gic_v3_its.h | 2 +-
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
index 72cf318810..63e28a7706 100644
--- a/xen/arch/arm/gic-v3-its.c
+++ b/xen/arch/arm/gic-v3-its.c
@@ -107,7 +107,7 @@ static int its_send_command(struct host_its
*hw_its, const void *its_cmd)
}
memcpy(hw_its->cmd_buf + writep, its_cmd, ITS_CMD_SIZE);
- if ( hw_its->flags & HOST_ITS_FLUSH_CMD_QUEUE )
+ if ( hw_its->flags & HOST_ITS_FLUSH_BUFFERS )
clean_dcache_va_range(hw_its->cmd_buf + writep, ITS_CMD_SIZE);
else
dsb(ishst);
@@ -335,7 +335,7 @@ static void *its_map_cbaser(struct host_its *its)
*/
if ( !(reg & GITS_BASER_INNER_CACHEABILITY_MASK) )
{
- its->flags |= HOST_ITS_FLUSH_CMD_QUEUE;
+ its->flags |= HOST_ITS_FLUSH_BUFFERS;
printk(XENLOG_WARNING "using non-cacheable ITS command
queue\n");
}
@@ -699,6 +699,9 @@ int gicv3_its_map_guest_device(struct domain *d,
if ( !itt_addr )
goto out_unlock;
+ if ( hw_its->flags & HOST_ITS_FLUSH_BUFFERS )
+ clean_dcache_va_range(itt_addr, nr_events * hw_its->itte_size);
... I think we need to have this flush unconditional like Linux does.
I forgot to mention that this likely want to be a
clean_dcache_and_invalidate_va_range() (see my comment in patch #2).
Cheers,
--
Julien Grall
