On 7/22/26 20:29, Peter Maydell wrote:
On Tue, 21 Jul 2026 at 18:06, Peter Maydell <[email protected]> wrote:
cc: to qemu-stable as a late "could we backport this (plus the
commit fixing a bug in this)" request...
On Wed, 10 Jun 2026 at 17:12, Peter Maydell <[email protected]> wrote:
From: Alex Bennée <[email protected]>
With the advent of WFE and WFI we need to pay closer attention to the
reason why the vCPU may be sleeping to figure out if we should wake
it up.
Create env->halt_reason to track this and then re-order the tests so
we:
- ignore everything is the vCPU is powered off
- wake up if the event_register is set and we were in a WFE
- otherwise any IRQ event does wake the vCPU up.
Reviewed-by: Richard Henderson <[email protected]>
Signed-off-by: Alex Bennée <[email protected]>
Message-id: [email protected]
Signed-off-by: Peter Maydell <[email protected]>
I didn't realize at the time, but this is actually fixing a bug,
which was just reported via the qemu-discuss list:
https://lists.gnu.org/archive/html/qemu-discuss/2026-07/msg00000.html
For M-profile, we already added SEV/WFE support, and that's in the
11.0 release, but arm_cpu_has_work() incorrectly checks for the
event register before it checks whether the CPU is powered off.
This only affects M-profile machines with multiple CPUs, and
the effect is that a SEV on core 0 incorrectly starts core 1
when it's powered down.
Could we backport this change (commit 6fd2fcdc61b70) plus the
bugfix followup (commit c2804566f654 "target/arm: do not clear
halting reason in has_work helper") to the 11.0.x branch, please?
(Earlier branches don't have SEV wake anything up so don't need
a backport.)
We could also do a simpler version of the fix for stable
branches if preferred, which is basically changing only
arm_cpu_has_work() to return false if cpu->power_state == PSCI_OFF
before looking at cpu->env.event_register.
Hm. And I missed this one when you emailed qemu-stable 2 days ago.
Just picked up these two commits. This will result in another
pipeline run for 11.0.x, but we're just in time :)
Thanks,
/mjt
