Re: [Xen-devel] [PATCH v3 00/15] Mem_event and mem_access for ARM

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

On Mon, Sep 1, 2014 at 9:56 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:

Hello Tamas

On 01/09/14 10:21, Tamas K Lengyel wrote:
> The ARM virtualization extension provides 2-stage paging, a similar mechanisms
> to Intel's EPT, which can be used to trace the memory accesses performed by
> the guest systems. This series moves the mem_access and mem_event codebase
> into Xen common, performs some code cleanup and architecture specific division
> of components, then sets up the necessary infrastructure in the ARM code
> to deliver the event on R/W/X traps. Finally, we turn on the compilation of
> mem_access and mem_event on ARM and perform the necessary changes to the
> tools side.
>
> This version of the series has been fully tested and is functional on an
> Arndale board.

domain_get_maximum_gpfn used in common code is defined as -ENOSYS.

Right, and I don't really understand why the safety check that uses this function never triggers in mem_access with this function just returning -errno.

I've sent a patch a month ago on the mailing list about it (see patch below).

Ian: Can you reconsider to apply the patch? (I will also reply to the thread). FYI,
I have a patch to fix xc_dom_gnttab_hvm_seed in libxc. I will try to send it next week.

Regards,

====================================================================

commit 7aa592b7a6f357b0003cd523e446d9d91dc96730
Author: Julien Grall <julien.grall@xxxxxxxxxx>
Date:   Mon Jun 30 17:21:13 2014 +0100

    xen/arm: Implement domain_get_maximum_gpfn

    The function domain_get_maximum_gpfn is returning the maximum gpfn ever
    mapped in the guest. We can use d->arch.p2m.max_mapped_gfn for this purpose.

    Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 0a243b0..e4a1e5e 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -954,7 +954,7 @@ int page_is_ram_type(unsigned long mfn, unsigned long mem_type)

 unsigned long domain_get_maximum_gpfn(struct domain *d)
 {
-    return -ENOSYS;
+    return d->arch.p2m.max_mapped_gfn;
 }

 void share_xen_page_with_guest(struct page_info *page,



--
Julien Grall

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