On 13/05/2024 17:14, Catalin Marinas wrote:
On Fri, Apr 12, 2024 at 09:42:05AM +0100, Steven Price wrote:
Override the set_fixmap_io to set shared permission for the host
in case of a CC guest. For now we mark it shared unconditionally.
Future changes could filter the physical address and make the
decision accordingly.
[...]
+void set_fixmap_io(enum fixed_addresses idx, phys_addr_t phys)
+{
+ pgprot_t prot = FIXMAP_PAGE_IO;
+
+ /*
+ * For now we consider all I/O as non-secure. For future
+ * filter the I/O base for setting appropriate permissions.
+ */
+ prot = __pgprot(pgprot_val(prot) | PROT_NS_SHARED);
+
+ return __set_fixmap(idx, phys, prot);
+}
I looked through the patches and could not find any place where this
function does anything different as per the commit log suggestion. Can
we just update FIXMAP_PAGE_IO for now until you have a clear use-case?
This gets used by the earlycon mapping. The commit description could be
made clear.
We may have to revisit this code to optionally apply the PROT_NS_SHARED
attribute, depending on whether this is a "protected MMIO" or not.
Suzuki
