Hi Denis,
On 05/06/2025 23:05, Julien Grall wrote:
Hi Denis,
On 28/05/2025 23:50, dm...@proton.me wrote:
From: Denis Mukhin <dm...@proton.me>
From: Denis Mukhin <dmuk...@ford.com>
Remove the hardcoded domain ID 0 allocation for hardware domain and
replace it
with a call to get_initial_domain_id() (returns the value of
hardware_domid on
Arm).
I am not entirely why this is done. Are you intending to pass a
different domain ID? If so...
Update domid_alloc(DOMID_INVALID) case to ensure that
get_initial_domain_id()
ID is skipped during domain ID allocation to cover domU case in dom0less
configuration. That also fixes a potential issue with re-using ID#0
for domUs
when get_initial_domain_id() returns non-zero.
Signed-off-by: Denis Mukhin <dmuk...@ford.com>
---
Changes since v8:
- rebased
---
xen/arch/arm/domain_build.c | 4 ++--
xen/common/device-tree/dom0less-build.c | 9 +++------
xen/common/domain.c | 4 ++--
3 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index e9d563c269..0ad80b020a 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2035,9 +2035,9 @@ void __init create_dom0(void)
... naming like create_dom0() probably wants to be renamed.
That said, I am not convinced a domain other than 0 should have full
privilege by default. So I would argue it should stay as ...
if ( !llc_coloring_enabled )
flags |= CDF_directmap;
- domid = domid_alloc(0);
+ domid = domid_alloc(get_initial_domain_id());
... 0.
Looking at the implementation of get_initial_domain_id(), I noticed the
behavior was changed for x86 by [1].
Before, get_initial_domain_id() was returning 0 except for the PV shim.
But now, it would could return the domain ID specified on the command
line (via hardware_dom).
From my understanding, the goal of the command line was to create the
hardware domain *after* boot. So initially we create dom0 and then
initialize the hardware domain. With the patch below, this has changed.
However, from the commit message, I don't understand why. It seems like
we broke late hwdom?
For instance, late_hwdom_init() has the following assert:
dom0 = rcu_lock_domain_by_id(0);
ASSERT(dom0 != NULL);
Jan, I saw you were involved in the review of the series. Any idea why
this was changed?
Cheers,
[1] https://lore.kernel.org/all/20250306075819.154361-1-dm...@proton.me/
--
Julien Grall
