[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/mm: switch to new APIs in arch_init_memory
Hi Hongyan, On 21/02/2020 10:42, Hongyan Xia wrote: From: Wei Liu <wei.liu2@xxxxxxxxxx> Since we now map and unmap Xen PTE pages, we would like to track the lifetime of mappings so that 1) we do not dereference memory through a variable after it is unmapped, 2) we do not unmap more than once. Therefore, we introduce the UNMAP_DOMAIN_PAGE macro to nullify the variable after unmapping, and ignore NULL in unmap_domain_page. If we want to support NULL in unmap_domain_page() then we would need to replicate the change for Arm as well. Cheers, Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx> Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx> --- xen/arch/x86/domain_page.c | 2 +- xen/arch/x86/mm.c | 14 ++++++++------ xen/include/xen/domain_page.h | 5 +++++ 3 files changed, 14 insertions(+), 7 deletions(-) diff --git a/xen/arch/x86/domain_page.c b/xen/arch/x86/domain_page.c index dd32712d2f..b03728e18e 100644 --- a/xen/arch/x86/domain_page.c +++ b/xen/arch/x86/domain_page.c @@ -181,7 +181,7 @@ void unmap_domain_page(const void *ptr) unsigned long va = (unsigned long)ptr, mfn, flags; struct vcpu_maphash_entry *hashent;- if ( va >= DIRECTMAP_VIRT_START )+ if ( !va || va >= DIRECTMAP_VIRT_START ) return;ASSERT(va >= MAPCACHE_VIRT_START && va < MAPCACHE_VIRT_END);diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 70b87c4830..9fcdcde5b7 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -356,19 +356,21 @@ void __init arch_init_memory(void) ASSERT(root_pgt_pv_xen_slots < ROOT_PAGETABLE_PV_XEN_SLOTS); if ( l4_table_offset(split_va) == l4_table_offset(split_va - 1) ) { - l3_pgentry_t *l3tab = alloc_xen_pagetable(); + mfn_t l3mfn = alloc_xen_pagetable_new();- if ( l3tab )+ if ( !mfn_eq(l3mfn, INVALID_MFN) ) { - const l3_pgentry_t *l3idle = - l4e_to_l3e(idle_pg_table[l4_table_offset(split_va)]); + l3_pgentry_t *l3idle = map_l3t_from_l4e( + idle_pg_table[l4_table_offset(split_va)]); + l3_pgentry_t *l3tab = map_domain_page(l3mfn);for ( i = 0; i < l3_table_offset(split_va); ++i )l3tab[i] = l3idle[i]; for ( ; i < L3_PAGETABLE_ENTRIES; ++i ) l3tab[i] = l3e_empty(); - split_l4e = l4e_from_mfn(virt_to_mfn(l3tab), - __PAGE_HYPERVISOR_RW); + split_l4e = l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR_RW); + UNMAP_DOMAIN_PAGE(l3idle); + UNMAP_DOMAIN_PAGE(l3tab); } else ++root_pgt_pv_xen_slots; diff --git a/xen/include/xen/domain_page.h b/xen/include/xen/domain_page.h index 32669a3339..a182d33b67 100644 --- a/xen/include/xen/domain_page.h +++ b/xen/include/xen/domain_page.h @@ -72,4 +72,9 @@ static inline void unmap_domain_page_global(const void *va) {};#endif /* !CONFIG_DOMAIN_PAGE */ +#define UNMAP_DOMAIN_PAGE(p) do { \+ unmap_domain_page(p); \ + (p) = NULL; \ +} while ( false ) + #endif /* __XEN_DOMAIN_PAGE_H__ */ -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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