Hi Michal,
On 2/26/2024 6:29 PM, Michal Orzel wrote:
Hi Henry,
On 26/02/2024 02:19, Henry Wang wrote:
An error message can seen from the init-dom0less application on
direct-mapped 1:1 domains:
```
Allocating magic pages
memory.c:238:d0v0 mfn 0x39000 doesn't belong to d1
Error on alloc magic pages
```
This is because populate_physmap() automatically assumes gfn == mfn
for direct mapped domains. This cannot be true for the magic pages
that are allocated later for Dom0less DomUs from the init-dom0less
helper application executed in Dom0.
Force populate_physmap to take the "normal" memory allocation route for
the magic pages even for 1:1 Dom0less DomUs. This should work as long
as the 1:1 Dom0less DomU doesn't have anything else mapped at the same
guest address as the magic pages:
- gfn 0x39000 address 0x39000000
- gfn 0x39001 address 0x39001000
- gfn 0x39002 address 0x39002000
- gfn 0x39003 address 0x39003000
Create helper is_magic_gpfn() for Arm to assist this and stub helpers
for non-Arm architectures to avoid #ifdef. Move the definition of the
magic pages on Arm to a more common place.
Note that the init-dom0less application of the diffenent Xen version
may allocate all or part of four magic pages for each DomU.
Reported-by: Alec Kwapis <[email protected]>
Signed-off-by: Stefano Stabellini <[email protected]>
Signed-off-by: Henry Wang <[email protected]>
NIT: Generally, the first SOB is the same as author of the patch.
I will fix in the next version. Thanks.
[...]
diff --git a/xen/common/memory.c b/xen/common/memory.c
index b3b05c2ec0..ab4bad79e2 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -219,7 +219,7 @@ static void populate_physmap(struct memop_args *a)
}
else
{
- if ( is_domain_direct_mapped(d) )
+ if ( is_domain_direct_mapped(d) && !is_magic_gpfn(gpfn) )
I struggle to understand the goal of this patch and the proposed solution.
The problem with magic pages applies to static mem domUs in general.
A direct mapped domU is a static mem domU whose memory is 1:1 mapped.
Let's say we try to map a magic page for a direct mapped domU. That check will
be false
and the execution will move to the next one i.e. is_domain_using_staticmem(d).
This check will be true and acquire_reserved_page() will fail instead (similar
to the
static mem (no direct map) scenario). The only thing that has changed is the
message.
Yes you are definitely correct, I missed the check for static mem
domains. Will fix in v2 once the proposal in the other thread is agreed.
Thanks for spotting this issue!
Kind regards,
Henry
~Michal
