[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen stable-4.13] x86/p2m: free the paging memory pool preemptively
commit 3e7aa35a56f9e9b42c74724c4083026da8ac9bcd Author: Roger Pau Monné <roger.pau@xxxxxxxxxx> AuthorDate: Tue Oct 11 15:50:10 2022 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Tue Oct 11 15:50:10 2022 +0200 x86/p2m: free the paging memory pool preemptively The paging memory pool is currently freed in two different places: from {shadow,hap}_teardown() via domain_relinquish_resources() and from {shadow,hap}_final_teardown() via complete_domain_destroy(). While the former does handle preemption, the later doesn't. Attempt to move as much p2m related freeing as possible to happen before the call to {shadow,hap}_teardown(), so that most memory can be freed in a preemptive way. In order to avoid causing issues to existing callers leave the root p2m page tables set and free them in {hap,shadow}_final_teardown(). Also modify {hap,shadow}_free to free the page immediately if the domain is dying, so that pages don't accumulate in the pool when {shadow,hap}_final_teardown() get called. Move altp2m_vcpu_disable_ve() to be done in hap_teardown(), as that's the place where altp2m_active gets disabled now. This is part of CVE-2022-33746 / XSA-410. Reported-by: Julien Grall <jgrall@xxxxxxxxxx> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Acked-by: Tim Deegan <tim@xxxxxxx> master commit: e7aa55c0aab36d994bf627c92bd5386ae167e16e master date: 2022-10-11 14:24:21 +0200 --- xen/arch/x86/domain.c | 7 ------- xen/arch/x86/mm/hap/hap.c | 39 +++++++++++++++++++++++++++++---------- xen/arch/x86/mm/shadow/common.c | 16 ++++++++++++++++ 3 files changed, 45 insertions(+), 17 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index 6199f36514..6996c6b06a 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -38,7 +38,6 @@ #include <xen/livepatch.h> #include <public/sysctl.h> #include <public/hvm/hvm_vcpu.h> -#include <asm/altp2m.h> #include <asm/regs.h> #include <asm/mc146818rtc.h> #include <asm/system.h> @@ -2098,12 +2097,6 @@ int domain_relinquish_resources(struct domain *d) vpmu_destroy(v); } - if ( altp2m_active(d) ) - { - for_each_vcpu ( d, v ) - altp2m_vcpu_disable_ve(v); - } - if ( is_pv_domain(d) ) { for_each_vcpu ( d, v ) diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c index 417b6ef37c..92b2014534 100644 --- a/xen/arch/x86/mm/hap/hap.c +++ b/xen/arch/x86/mm/hap/hap.c @@ -28,6 +28,7 @@ #include <xen/domain_page.h> #include <xen/guest_access.h> #include <xen/keyhandler.h> +#include <asm/altp2m.h> #include <asm/event.h> #include <asm/page.h> #include <asm/current.h> @@ -532,18 +533,8 @@ void hap_final_teardown(struct domain *d) unsigned int i; if ( hvm_altp2m_supported() ) - { - d->arch.altp2m_active = 0; - - if ( d->arch.altp2m_eptp ) - { - free_xenheap_page(d->arch.altp2m_eptp); - d->arch.altp2m_eptp = NULL; - } - for ( i = 0; i < MAX_ALTP2M; i++ ) p2m_teardown(d->arch.altp2m_p2m[i], true); - } /* Destroy nestedp2m's first */ for (i = 0; i < MAX_NESTEDP2M; i++) { @@ -558,6 +549,8 @@ void hap_final_teardown(struct domain *d) paging_lock(d); hap_set_allocation(d, 0, NULL); ASSERT(d->arch.paging.hap.p2m_pages == 0); + ASSERT(d->arch.paging.hap.free_pages == 0); + ASSERT(d->arch.paging.hap.total_pages == 0); paging_unlock(d); } @@ -565,6 +558,7 @@ void hap_teardown(struct domain *d, bool *preempted) { struct vcpu *v; mfn_t mfn; + unsigned int i; ASSERT(d->is_dying); ASSERT(d != current->domain); @@ -586,6 +580,31 @@ void hap_teardown(struct domain *d, bool *preempted) } } + paging_unlock(d); + + /* Leave the root pt in case we get further attempts to modify the p2m. */ + if ( hvm_altp2m_supported() ) + { + if ( altp2m_active(d) ) + for_each_vcpu ( d, v ) + altp2m_vcpu_disable_ve(v); + + d->arch.altp2m_active = 0; + + FREE_XENHEAP_PAGE(d->arch.altp2m_eptp); + + for ( i = 0; i < MAX_ALTP2M; i++ ) + p2m_teardown(d->arch.altp2m_p2m[i], false); + } + + /* Destroy nestedp2m's after altp2m. */ + for ( i = 0; i < MAX_NESTEDP2M; i++ ) + p2m_teardown(d->arch.nested_p2m[i], false); + + p2m_teardown(p2m_get_hostp2m(d), false); + + paging_lock(d); + if ( d->arch.paging.hap.total_pages != 0 ) { hap_set_allocation(d, 0, preempted); diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c index c178b9a5d8..8679620f18 100644 --- a/xen/arch/x86/mm/shadow/common.c +++ b/xen/arch/x86/mm/shadow/common.c @@ -2791,6 +2791,19 @@ void shadow_teardown(struct domain *d, bool *preempted) } } + paging_unlock(d); + + p2m_teardown(p2m_get_hostp2m(d), false); + + paging_lock(d); + + /* + * Reclaim all shadow memory so that shadow_set_allocation() doesn't find + * in-use pages, as _shadow_prealloc() will no longer try to reclaim pages + * because the domain is dying. + */ + shadow_blow_tables(d); + #if (SHADOW_OPTIMIZATIONS & (SHOPT_VIRTUAL_TLB|SHOPT_OUT_OF_SYNC)) /* Free the virtual-TLB array attached to each vcpu */ for_each_vcpu(d, v) @@ -2909,6 +2922,9 @@ void shadow_final_teardown(struct domain *d) d->arch.paging.shadow.total_pages, d->arch.paging.shadow.free_pages, d->arch.paging.shadow.p2m_pages); + ASSERT(!d->arch.paging.shadow.total_pages); + ASSERT(!d->arch.paging.shadow.free_pages); + ASSERT(!d->arch.paging.shadow.p2m_pages); paging_unlock(d); } -- generated by git-patchbot for /home/xen/git/xen.git#stable-4.13
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