[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] RT Xen on ARM - R-Car series


On 01.02.19 19:40, Julien Grall wrote:
On 01/02/2019 16:53, Roger Pau Monné wrote:
On Thu, Jan 31, 2019 at 11:14:37PM +0000, Julien Grall wrote:
On 1/31/19 9:56 PM, Stefano Stabellini wrote:
On Thu, 31 Jan 2019, Julien Grall wrote:
On 31/01/2019 12:00, Andrii Anisov wrote:
On 31.01.19 13:37, Julien Grall wrote:
So, I've got a hacky patch to 'fix' this on x86, by taking a reference
to the mfn behind the virtual address provided when setting up the
hypercall and mapping it in Xen.

That was the idea I had in mind :).
Looks interesting.

Hopefully, no guest is modifying the mapping (i.e the virtual address point to 
a different physical address) afterwards.
I guess, that mapping should not be moved around. Otherwise it would be broken 
even with the current implementation.
Moreover, having that buffer mapped to XEN will reduce context switch time as a 
side effect.

This however doesn't work on ARM due
to the lack of paging_gva_to_gfn. I guess there's something similar to
translate a guest virtual address into a gfn or a mfn?

get_page_from_gva should to the job for you.
+int map_runstate_area(struct vcpu *v,
+                      struct vcpu_register_runstate_memory_area *area)
+    unsigned long offset;
+    unsigned int i;
+    struct domain *d = v->domain;
+    size_t size =
+        has_32bit_shinfo((v)->domain) ? sizeof(*v->compat_runstate_guest) :
+                                        sizeof(*v->runstate_guest);
+    if ( v->runstate_guest )
+    {
+        return -EBUSY;
+    }
+    offset = area->addr.p & ~PAGE_MASK;
+    for ( i = 0; i < ARRAY_SIZE(v->runstate_mfn); i++ )
+    {
+        p2m_type_t t;
+        uint32_t pfec = PFEC_page_present;
+        gfn_t gfn = _gfn(paging_gva_to_gfn(v, area->addr.p, &pfec));
+        struct page_info *pg;
+        if ( gfn_eq(gfn, INVALID_GFN) )
+            return -EFAULT;
+        v->runstate_mfn[i] = get_gfn(d, gfn_x(gfn), &t);

get_gfn would need to be implemented on Arm.
I'm going to step into this, tomorrow I guess. I have to finish smth today.

Andrii Anisov.

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.