(+ Andrew and Jan)
Hi,
On 11/10/2019 01:27, Stefano Stabellini wrote:
On Thu, 10 Oct 2019, Julien Grall wrote:
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index be23acfe26..a6637ce347 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -964,11 +964,40 @@ static int create_xen_table(lpae_t *entry)
static lpae_t *xen_map_table(mfn_t mfn)
{
+ /*
+ * We may require to map the page table before map_domain_page() is
+ * useable. The requirements here is it must be useable as soon as
+ * page-tables are allocated dynamically via alloc_boot_pages().
+ *
+ * We need to do the check on physical address rather than virtual
+ * address to avoid truncation on Arm32. Therefore is_kernel() cannot
+ * be used.
+ */
+ if ( system_state == SYS_STATE_early_boot )
+ {
+ const mfn_t mstart = virt_to_mfn(_start);
+ const mfn_t mend = virt_to_mfn(_end);
+
+ if ( (mfn_x(mstart) <= mfn_x(mfn)) && (mfn_x(mfn) < mfn_x(mend)) )
+ {
The patch is good. Actually I noticed that we already have
is_xen_fixed_mfn(), looks like it is made for this. I think we should
use it here, except that is_xen_fixed_mfn has:
Thanks, I thought we had one but I couldn't remember the name :(.
(mfn_to_maddr(mfn) <= virt_to_maddr(&_end)))
I think it should actually be:
(mfn_to_maddr(mfn) < virt_to_maddr(&_end)))
Maybe we could fix that at the same time in one patch? However, it is
the same definition as on x86, so I don't know what is going on there.
For Arm we should definitely use < and not <=.
I am assuming this is the same for x86. Andrew? Jan?
Cheers,
--
Julien Grall
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