[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] xen/arm: Construct the P2M pages pool for guests
commit 55914f7fc91a468649b8a3ec3f53ae1c4aca6670 Author: Henry Wang <Henry.Wang@xxxxxxx> AuthorDate: Mon Jun 6 06:17:28 2022 +0000 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Tue Oct 11 14:28:39 2022 +0200 xen/arm: Construct the P2M pages pool for guests This commit constructs the p2m pages pool for guests from the data structure and helper perspective. This is implemented by: - Adding a `struct paging_domain` which contains a freelist, a counter variable and a spinlock to `struct arch_domain` to indicate the free p2m pages and the number of p2m total pages in the p2m pages pool. - Adding a helper `p2m_get_allocation` to get the p2m pool size. - Adding a helper `p2m_set_allocation` to set the p2m pages pool size. This helper should be called before allocating memory for a guest. - Adding a helper `p2m_teardown_allocation` to free the p2m pages pool. This helper should be called during the xl domain destory. This is part of CVE-2022-33747 / XSA-409. Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> --- xen/arch/arm/include/asm/domain.h | 10 +++++ xen/arch/arm/include/asm/p2m.h | 4 ++ xen/arch/arm/p2m.c | 88 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 102 insertions(+) diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h index 26a8348eed..2ce6764322 100644 --- a/xen/arch/arm/include/asm/domain.h +++ b/xen/arch/arm/include/asm/domain.h @@ -53,6 +53,14 @@ struct vtimer { uint64_t cval; }; +struct paging_domain { + spinlock_t lock; + /* Free P2M pages from the pre-allocated P2M pool */ + struct page_list_head p2m_freelist; + /* Number of pages from the pre-allocated P2M pool */ + unsigned long p2m_total_pages; +}; + struct arch_domain { #ifdef CONFIG_ARM_64 @@ -64,6 +72,8 @@ struct arch_domain struct hvm_domain hvm; + struct paging_domain paging; + struct vmmio vmmio; /* Continuable domain_relinquish_resources(). */ diff --git a/xen/arch/arm/include/asm/p2m.h b/xen/arch/arm/include/asm/p2m.h index a15ea67f9b..42bfd548c4 100644 --- a/xen/arch/arm/include/asm/p2m.h +++ b/xen/arch/arm/include/asm/p2m.h @@ -218,6 +218,10 @@ void p2m_restore_state(struct vcpu *n); /* Print debugging/statistial info about a domain's p2m */ void p2m_dump_info(struct domain *d); +unsigned int p2m_get_allocation(struct domain *d); +int p2m_set_allocation(struct domain *d, unsigned long pages, bool *preempted); +int p2m_teardown_allocation(struct domain *d); + static inline void p2m_write_lock(struct p2m_domain *p2m) { write_lock(&p2m->lock); diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index b445f4d754..db385fe410 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -44,6 +44,92 @@ static uint64_t generate_vttbr(uint16_t vmid, mfn_t root_mfn) return (mfn_to_maddr(root_mfn) | ((uint64_t)vmid << 48)); } +/* Return the size of the pool, rounded up to the nearest MB */ +unsigned int p2m_get_allocation(struct domain *d) +{ + unsigned long nr_pages = ACCESS_ONCE(d->arch.paging.p2m_total_pages); + + return ROUNDUP(nr_pages, 1 << (20 - PAGE_SHIFT)) >> (20 - PAGE_SHIFT); +} + +/* + * Set the pool of pages to the required number of pages. + * Returns 0 for success, non-zero for failure. + * Call with d->arch.paging.lock held. + */ +int p2m_set_allocation(struct domain *d, unsigned long pages, bool *preempted) +{ + struct page_info *pg; + + ASSERT(spin_is_locked(&d->arch.paging.lock)); + + for ( ; ; ) + { + if ( d->arch.paging.p2m_total_pages < pages ) + { + /* Need to allocate more memory from domheap */ + pg = alloc_domheap_page(NULL, 0); + if ( pg == NULL ) + { + printk(XENLOG_ERR "Failed to allocate P2M pages.\n"); + return -ENOMEM; + } + ACCESS_ONCE(d->arch.paging.p2m_total_pages) = + d->arch.paging.p2m_total_pages + 1; + page_list_add_tail(pg, &d->arch.paging.p2m_freelist); + } + else if ( d->arch.paging.p2m_total_pages > pages ) + { + /* Need to return memory to domheap */ + pg = page_list_remove_head(&d->arch.paging.p2m_freelist); + if( pg ) + { + ACCESS_ONCE(d->arch.paging.p2m_total_pages) = + d->arch.paging.p2m_total_pages - 1; + free_domheap_page(pg); + } + else + { + printk(XENLOG_ERR + "Failed to free P2M pages, P2M freelist is empty.\n"); + return -ENOMEM; + } + } + else + break; + + /* Check to see if we need to yield and try again */ + if ( preempted && general_preempt_check() ) + { + *preempted = true; + return -ERESTART; + } + } + + return 0; +} + +int p2m_teardown_allocation(struct domain *d) +{ + int ret = 0; + bool preempted = false; + + spin_lock(&d->arch.paging.lock); + if ( d->arch.paging.p2m_total_pages != 0 ) + { + ret = p2m_set_allocation(d, 0, &preempted); + if ( preempted ) + { + spin_unlock(&d->arch.paging.lock); + return -ERESTART; + } + ASSERT(d->arch.paging.p2m_total_pages == 0); + } + spin_unlock(&d->arch.paging.lock); + + return ret; +} + /* Unlock the flush and do a P2M TLB flush if necessary */ void p2m_write_unlock(struct p2m_domain *p2m) { @@ -1623,7 +1709,9 @@ int p2m_init(struct domain *d) unsigned int cpu; rwlock_init(&p2m->lock); + spin_lock_init(&d->arch.paging.lock); INIT_PAGE_LIST_HEAD(&p2m->pages); + INIT_PAGE_LIST_HEAD(&d->arch.paging.p2m_freelist); p2m->vmid = INVALID_VMID; -- generated by git-patchbot for /home/xen/git/xen.git#staging
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