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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-02-28 17:58:48 -0500
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-04-18 11:10:27 -0400
commitcf8d91633ddef9e816ccbf3da833c79ce508988d (patch)
tree7d994ec0f3b7d3a2bdddabd85493d190f4019d85 /arch/x86/xen
parent1eff1ad0285038e309a81da4a004f071608309fb (diff)
xen/p2m/m2p/gnttab: Support GNTMAP_host_map in the M2P override.
We only supported the M2P (and P2M) override only for the GNTMAP_contains_pte type mappings. Meaning that we grants operations would "contain the machine address of the PTE to update" If the flag is unset, then the grant operation is "contains a host virtual address". The latter case means that the Hypervisor takes care of updating our page table (specifically the PTE entry) with the guest's MFN. As such we should not try to do anything with the PTE. Previous to this patch we would try to clear the PTE which resulted in Xen hypervisor being upset with us: (XEN) mm.c:1066:d0 Attempt to implicitly unmap a granted PTE c0100000ccc59067 (XEN) domain_crash called from mm.c:1067 (XEN) Domain 0 (vcpu#0) crashed on cpu#3: (XEN) ----[ Xen-4.0-110228 x86_64 debug=y Not tainted ]---- and crashing us. This patch allows us to inhibit the PTE clearing in the PV guest if the GNTMAP_contains_pte is not set. On the m2p_remove_override path we provide the same parameter. Sadly in the grant-table driver we do not have a mechanism to tell m2p_remove_override whether to clear the PTE or not. Since the grant-table driver is used by user-space, we can safely assume that it operates only on PTE's. Hence the implementation for it to work on !GNTMAP_contains_pte returns -EOPNOTSUPP. In the future we can implement the support for this. It will require some extra accounting structure to keep track of the page[i], and the flag. [v1: Added documentation details, made it return -EOPNOTSUPP instead of trying to do a half-way implementation] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'arch/x86/xen')
-rw-r--r--arch/x86/xen/p2m.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 141eb0de8b06..2d2b32af3a1d 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -650,7 +650,7 @@ static unsigned long mfn_hash(unsigned long mfn)
650} 650}
651 651
652/* Add an MFN override for a particular page */ 652/* Add an MFN override for a particular page */
653int m2p_add_override(unsigned long mfn, struct page *page) 653int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte)
654{ 654{
655 unsigned long flags; 655 unsigned long flags;
656 unsigned long pfn; 656 unsigned long pfn;
@@ -662,7 +662,6 @@ int m2p_add_override(unsigned long mfn, struct page *page)
662 if (!PageHighMem(page)) { 662 if (!PageHighMem(page)) {
663 address = (unsigned long)__va(pfn << PAGE_SHIFT); 663 address = (unsigned long)__va(pfn << PAGE_SHIFT);
664 ptep = lookup_address(address, &level); 664 ptep = lookup_address(address, &level);
665
666 if (WARN(ptep == NULL || level != PG_LEVEL_4K, 665 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
667 "m2p_add_override: pfn %lx not mapped", pfn)) 666 "m2p_add_override: pfn %lx not mapped", pfn))
668 return -EINVAL; 667 return -EINVAL;
@@ -674,10 +673,9 @@ int m2p_add_override(unsigned long mfn, struct page *page)
674 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) 673 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
675 return -ENOMEM; 674 return -ENOMEM;
676 675
677 if (!PageHighMem(page)) 676 if (clear_pte && !PageHighMem(page))
678 /* Just zap old mapping for now */ 677 /* Just zap old mapping for now */
679 pte_clear(&init_mm, address, ptep); 678 pte_clear(&init_mm, address, ptep);
680
681 spin_lock_irqsave(&m2p_override_lock, flags); 679 spin_lock_irqsave(&m2p_override_lock, flags);
682 list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); 680 list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
683 spin_unlock_irqrestore(&m2p_override_lock, flags); 681 spin_unlock_irqrestore(&m2p_override_lock, flags);
@@ -685,7 +683,7 @@ int m2p_add_override(unsigned long mfn, struct page *page)
685 return 0; 683 return 0;
686} 684}
687 685
688int m2p_remove_override(struct page *page) 686int m2p_remove_override(struct page *page, bool clear_pte)
689{ 687{
690 unsigned long flags; 688 unsigned long flags;
691 unsigned long mfn; 689 unsigned long mfn;
@@ -713,7 +711,7 @@ int m2p_remove_override(struct page *page)
713 spin_unlock_irqrestore(&m2p_override_lock, flags); 711 spin_unlock_irqrestore(&m2p_override_lock, flags);
714 set_phys_to_machine(pfn, page->index); 712 set_phys_to_machine(pfn, page->index);
715 713
716 if (!PageHighMem(page)) 714 if (clear_pte && !PageHighMem(page))
717 set_pte_at(&init_mm, address, ptep, 715 set_pte_at(&init_mm, address, ptep,
718 pfn_pte(pfn, PAGE_KERNEL)); 716 pfn_pte(pfn, PAGE_KERNEL));
719 /* No tlb flush necessary because the caller already 717 /* No tlb flush necessary because the caller already