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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