Hi Tamas,
On 08/12/16 22:57, Tamas K Lengyel wrote:
This patch relocates mem_access components that are currently mixed with p2m
code into separate files. This better aligns the code with similar subsystems,
such as mem_sharing and mem_paging, which are already in separate files. There
are no code-changes introduced, the patch is mechanical code movement.
Whilst I agree this is a good move in general, the ARM (both 32bits and
64bits) code deserves more attention to make it work in *all* the case.
It would have been nice to show that by addressing my concerns when you
first suggested this move (see [1]).
On ARM we also relocate the static inline gfn_next_boundary function to p2m.h
as it is a function the mem_access code needs access to.
Signed-off-by: Tamas K Lengyel <tamas.leng...@zentific.com>
[...]
+/*
+ * Lookup the MFN corresponding to a domain's GFN.
+ * Lookup mem access in the ratrix tree.
+ * The entries associated to the GFN is considered valid.
+ */
+p2m_access_t p2m_mem_access_radix_get(struct p2m_domain *p2m, gfn_t gfn)
[...]
+int p2m_mem_access_radix_set(struct p2m_domain *p2m, gfn_t gfn,
+ p2m_access_t a)
[...]
The radix tree functions should stay in p2m.c as they are tie to stage-2
page table handling.
+
+/*
+ * If mem_access is in use it might have been the reason why get_page_from_gva
+ * failed to fetch the page, as it uses the MMU for the permission checking.
+ * Only in these cases we do a software-based type check and fetch the page if
+ * we indeed found a conflicting mem_access setting.
+ */
+struct page_info*
+p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned long flag)
This interface should take a vCPU in parameter and not rely on current.
Also, p2m_mem_access_check_get_page is using the hardware to translate a
VA to an IPA. This only works if the memory where the stage-1 page
tables reside is not protected. The upcoming support of altp2m will make
things trickier.
[1]
https://lists.xenproject.org/archives/html/xen-devel/2016-08/msg00037.html
--
Julien Grall
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