On 23.07.25 12:16, Julien Grall wrote:
Hi,
On 23/07/2025 08:58, Grygorii Strashko wrote:
From: Grygorii Strashko <grygorii_stras...@epam.com>
Move vcpu_switch_to_aarch64_mode() in arch_vcpu_create() callback instead
of calling it manually from few different places after vcpu_create().
Before doing above ensure vcpu0 is created after kernel_probe() is done and
domain's guest execution mode (32-bit/64-bit) is set for dom0 and dom0less
domains.
The commit message doesn't mention anything about domains created by the
toolstack. In this case, from my understanding, the switch to 64-bit domain
happens *after* the vCPUs are created.
At the moment, I think this is probably ok to call...
Signed-off-by: Grygorii Strashko <grygorii_stras...@epam.com>
---
xen/arch/arm/domain.c | 3 +++
xen/arch/arm/domain_build.c | 13 +++++--------
xen/common/device-tree/dom0less-build.c | 6 +++---
xen/include/asm-generic/dom0less-build.h | 2 +-
4 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 79a144e61be9..bbd4a764c696 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -586,6 +586,9 @@ int arch_vcpu_create(struct vcpu *v)
if ( get_ssbd_state() == ARM_SSBD_RUNTIME )
v->arch.cpu_info->flags |= CPUINFO_WORKAROUND_2_FLAG;
+ if ( is_64bit_domain(v->domain) )
+ vcpu_switch_to_aarch64_mode(v);
... this function here because I *think* it would be NOP. But this feels really
fragile.
The toolstack configures domain and vcpus through XEN_DOMCTL_set_address_size
on Arm64:
- toolstack creates domain and parses kernel binary: domain created with
DOMAIN_32BIT mode by default
- toolstack creates vcpus (still 32 bit mode):
libxl__build_pre()->xc_domain_max_vcpus()
- toolstack switches domain mode depending on kernel binary type:
libxl__build_dom()->xc_dom_boot_mem_init(),
which triggers XEN_DOMCTL_set_address_size hypercall.
Xen: arm64: switches domain mode and re-configures vcpus:
subarch_do_domctl()->set_address_size()
So, this patch does not affect toolstack path, only optimizes Xen boots a bit.
Also, during Xen boot or by toolstack - the domain is always created before
it's type is even known, which, in turn,
is based on guest binary which is parsed later during domain configuration
stage.
I can add note in commit message "This patch doesn't affect on the toolstack
Arm64 domain creation path as toolstack always
re-configures domain mode and vcpus through XEN_DOMCTL_set_address_size hypercall
during domain configuration stage"
If the desire is to make 32-bit domain optional on Arm64. Then I think it would
be better to pass the domain type when the domain
is created (IOW add an extra flags to XEN_DOMCTL_createdomain). This will
require more work, but it will be a lot more robust.
--
Best regards,
-grygorii
