From: Jan Beulich Date: Mon, 21 Dec 2015 12:35:13 +0000 (+0100) Subject: VMX: allocate APIC access page from domain heap X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~2040 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=a2b4b8c20413302c0983b730925d59dc2fee3bb3;p=xen.git VMX: allocate APIC access page from domain heap ... since we don't need its virtual address anywhere (it's a placeholder page only after all). For this to work (and possibly be done elsewhere too) share_xen_page_with_guest() needs to mark pages handed to it as Xen heap ones. To be on the safe side, also explicitly clear the page (not having done so was okay due to the XSA-100 fix, but is still a latent bug since we don't formally guarantee allocations to come out zeroed, and in fact this property may disappear again as soon as the asynchronous runtime scrubbing patches arrive). Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper Acked-by: Kevin Tian --- diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 2922673292..e056515c82 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -2489,18 +2489,21 @@ gp_fault: static int vmx_alloc_vlapic_mapping(struct domain *d) { - void *apic_va; + struct page_info *pg; + unsigned long mfn; if ( !cpu_has_vmx_virtualize_apic_accesses ) return 0; - apic_va = alloc_xenheap_page(); - if ( apic_va == NULL ) + pg = alloc_domheap_page(d, MEMF_no_owner); + if ( !pg ) return -ENOMEM; - share_xen_page_with_guest(virt_to_page(apic_va), d, XENSHARE_writable); - d->arch.hvm_domain.vmx.apic_access_mfn = virt_to_mfn(apic_va); - set_mmio_p2m_entry(d, paddr_to_pfn(APIC_DEFAULT_PHYS_BASE), - _mfn(virt_to_mfn(apic_va)), p2m_get_hostp2m(d)->default_access); + mfn = page_to_mfn(pg); + clear_domain_page(_mfn(mfn)); + share_xen_page_with_guest(pg, d, XENSHARE_writable); + d->arch.hvm_domain.vmx.apic_access_mfn = mfn; + set_mmio_p2m_entry(d, paddr_to_pfn(APIC_DEFAULT_PHYS_BASE), _mfn(mfn), + p2m_get_hostp2m(d)->default_access); return 0; } @@ -2508,8 +2511,9 @@ static int vmx_alloc_vlapic_mapping(struct domain *d) static void vmx_free_vlapic_mapping(struct domain *d) { unsigned long mfn = d->arch.hvm_domain.vmx.apic_access_mfn; + if ( mfn != 0 ) - free_xenheap_page(mfn_to_virt(mfn)); + free_shared_domheap_page(mfn_to_page(mfn)); } static void vmx_install_vlapic_mapping(struct vcpu *v) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 92df36fa19..d33eb10e9d 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -454,7 +454,7 @@ void share_xen_page_with_guest( /* Only add to the allocation list if the domain isn't dying. */ if ( !d->is_dying ) { - page->count_info |= PGC_allocated | 1; + page->count_info |= PGC_xen_heap | PGC_allocated | 1; if ( unlikely(d->xenheap_pages++ == 0) ) get_knownalive_domain(d); page_list_add_tail(page, &d->xenpage_list); @@ -469,6 +469,17 @@ void share_xen_page_with_privileged_guests( share_xen_page_with_guest(page, dom_xen, readonly); } +void free_shared_domheap_page(struct page_info *page) +{ + if ( test_and_clear_bit(_PGC_allocated, &page->count_info) ) + put_page(page); + if ( !test_and_clear_bit(_PGC_xen_heap, &page->count_info) ) + ASSERT_UNREACHABLE(); + page->u.inuse.type_info = 0; + page_set_owner(page, NULL); + free_domheap_page(page); +} + void make_cr3(struct vcpu *v, unsigned long mfn) { v->arch.cr3 = mfn << PAGE_SHIFT; diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h index 67b34c65a3..1f5e335a29 100644 --- a/xen/include/asm-x86/mm.h +++ b/xen/include/asm-x86/mm.h @@ -276,6 +276,7 @@ extern void share_xen_page_with_guest( struct page_info *page, struct domain *d, int readonly); extern void share_xen_page_with_privileged_guests( struct page_info *page, int readonly); +extern void free_shared_domheap_page(struct page_info *page); #define frame_table ((struct page_info *)FRAMETABLE_VIRT_START) #define spage_table ((struct spage_info *)SPAGETABLE_VIRT_START)