Thanks for suggestion. I'm always nervous on API changes.
I'm still considering if any other potential usage mode for patch 5/6l (i.e.
change page table or exchange memory for other domain),, but frustratedly
realize no other requirement.
Thanks
-- jyh
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote:
> I'd pack an extra domid into the top 16 bits of the foreigndom
> parameter to mmu_update(). Bottom 16 bits remain foreign owner of data
> page. Upper 16
> bits, if non-zero, are foreign owner of pt page (we could make
> this field +1
> so that dom0 can be encoded as well).
>
> -- Keir
>
> On 01/06/2009 07:24, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:
>
>> I want to clarify that this patch need more discussion because there
>> is no clear way to distinguish if the page table address (i.e.
>> address passed in req[:2] ) is owned by the current domain or by the
>> foreign domain. So I just try to check if mfn_valid(), but I suspect
>> if this is the right method.
>>
>> Thanks
>> Yunhong Jiang
>>
>> xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote:
>>> foreign domain
>>>
>>> Currently MMU_PT_UPDATE_RESERVE_AD support only update page
>>> table for current domain. This patch add support for foreign domain
>>> also.
>>>
>>> Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx> Update
>>> the page table update hypercall
>>>
>>> diff -r f6457425560b xen/arch/x86/mm.c
>>> --- a/xen/arch/x86/mm.c Wed May 27 03:22:43 2009 +0800
>>> +++ b/xen/arch/x86/mm.c Wed May 27 03:40:38 2009 +0800 @@ -110,6
>>> +110,7 @@ #include <asm/hypercall.h>
>>> #include <asm/shared.h>
>>> #include <public/memory.h>
>>> +#include <public/sched.h>
>>> #include <xsm/xsm.h>
>>> #include <xen/trace.h>
>>>
>>> @@ -2990,7 +2991,8 @@ int do_mmu_update(
>>> struct page_info *page;
>>> int rc = 0, okay = 1, i = 0;
>>> unsigned int cmd, done = 0;
>>> - struct domain *d = current->domain;
>>> + struct domain *d = current->domain, *pt_owner = NULL;
>>> + struct vcpu *v = current;
>>> struct domain_mmap_cache mapcache;
>>>
>>> if ( unlikely(count & MMU_UPDATE_PREEMPTED) )
>>> @@ -3051,10 +3053,35 @@ int do_mmu_update(
>>> gmfn = req.ptr >> PAGE_SHIFT;
>>> mfn = gmfn_to_mfn(d, gmfn);
>>>
>>> - if ( unlikely(!get_page_from_pagenr(mfn, d)) )
>>> + if (!mfn_valid(mfn))
>>> + mfn = gmfn_to_mfn(FOREIGNDOM, gmfn);
>>> + if (!mfn_valid(mfn))
>>> {
>>> MEM_LOG("Could not get page for normal update");
>>> break; + } +
>>> + pt_owner =
>>> page_get_owner_and_reference(mfn_to_page(mfn)); + + if (
>>> pt_owner != d ) + {
>>> + if ( pt_owner == FOREIGNDOM )
>>> + {
>>> + spin_lock(&FOREIGNDOM->shutdown_lock);
>>> + if ( !IS_PRIV(d) ||
>>> + !FOREIGNDOM->is_shut_down ||
>>> + (FOREIGNDOM->shutdown_code !=
>>> SHUTDOWN_suspend) ) + {
>>> + spin_unlock(&FOREIGNDOM->shutdown_lock);
>>> + rc = -EPERM;
>>> + break;
>>> + }
>>> + v = FOREIGNDOM->vcpu[0];
>>> + }else
>>> + {
>>> + rc = -EPERM;
>>> + break;
>>> + }
>>> }
>>>
>>> va = map_domain_page_with_cache(mfn, &mapcache);
>>> @@ -3070,24 +3097,21 @@ int do_mmu_update(
>>> {
>>> l1_pgentry_t l1e = l1e_from_intpte(req.val);
>>> okay = mod_l1_entry(va, l1e, mfn,
>>> - cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD,
>>> - current);
>>> + cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD, v);
>>> }
>>> break;
>>> case PGT_l2_page_table:
>>> {
>>> l2_pgentry_t l2e = l2e_from_intpte(req.val);
>>> okay = mod_l2_entry(va, l2e, mfn,
>>> - cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD,
>>> - current);
>>> + cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD, v);
>>> }
>>> break;
>>> case PGT_l3_page_table:
>>> {
>>> l3_pgentry_t l3e = l3e_from_intpte(req.val);
>>> rc = mod_l3_entry(va, l3e, mfn,
>>> - cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD, 1,
>>> - current);
>>> + cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD, 1, v);
>>> okay = !rc;
>>> }
>>> break;
>>> @@ -3096,8 +3120,7 @@ int do_mmu_update(
>>> {
>>> l4_pgentry_t l4e = l4e_from_intpte(req.val);
>>> rc = mod_l4_entry(va, l4e, mfn,
>>> - cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD, 1,
>>> - current);
>>> + cmd ==
>>> MMU_PT_UPDATE_PRESERVE_AD, 1, v);
>>> okay = !rc;
>>> }
>>> break;
>>> @@ -3105,7 +3128,7 @@ int do_mmu_update(
>>> case PGT_writable_page:
>>> perfc_incr(writable_mmu_updates);
>>> okay = paging_write_guest_entry(
>>> - current, va, req.val, _mfn(mfn));
>>> + v, va, req.val, _mfn(mfn));
>>> break; } page_unlock(page);
>>> @@ -3116,11 +3139,13 @@ int do_mmu_update(
>>> {
>>> perfc_incr(writable_mmu_updates);
>>> okay = paging_write_guest_entry(
>>> - current, va, req.val, _mfn(mfn));
>>> + v, va, req.val, _mfn(mfn));
>>> put_page_type(page);
>>> }
>>>
>>> unmap_domain_page_with_cache(va, &mapcache);
>>> + if (pt_owner != d)
>>> + spin_unlock(&FOREIGNDOM->shutdown_lock);
>>> put_page(page); break;
>>>
>>> diff -r f6457425560b xen/include/public/xen.h
>>> --- a/xen/include/public/xen.h Wed May 27 03:22:43 2009 +0800
>>> +++ b/xen/include/public/xen.h Wed May 27 03:26:46 2009 +0800
>>> @@ -170,6 +170,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_pfn_t);
>>> * table entry is valid/present, the mapped frame must belong
>>> to the FD, if
>>> * an FD has been specified. If attempting to map an I/O page then
>>> the
>>> * caller assumes the privilege of the FD.
>>> + * The page table entry normally belongs to the calling
>>> domain. Otherwise it
>>> + * should belong to the FD and the FD should be suspended already
>>> * FD == DOMID_IO: Permit /only/ I/O mappings, at the priv
>>> level of the caller.
>>> * FD == DOMID_XEN: Map restricted areas of Xen's heap space.
>>> * ptr[:2] -- Machine address of the page-table entry to modify.
>
>
>
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