diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index 47b54c792e..39680eeb6e 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -6,6 +6,7 @@ #include #include +#include #include #define MAX_VMID_8_BIT (1UL << 8) @@ -1430,6 +1431,8 @@ struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t va, struct page_info *page = NULL; paddr_t maddr = 0; uint64_t par; + mfn_t mfn; + p2m_type_t t; /* * XXX: To support a different vCPU, we would need to load the @@ -1446,8 +1449,29 @@ struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t va, par = gvirt_to_maddr(va, &maddr, flags); p2m_read_unlock(p2m); + /* + * gvirt_to_maddr may fail if the entry does not have the valid bit + * set. Fallback to the second method: + * 1) Translate the VA to IPA using software lookup -> Stage-1 page-table + * may not be accessible because the stage-2 entries may have valid + * bit unset. + * 2) Software lookup of the MFN + * + * Note that when memaccess is enabled, we instead call directly + * p2m_mem_access_check_and_get_page(...). Because the function is a + * a variant of the methods described above, it will be able to + * handle entries with valid bit unset. + * + * TODO: Integrate more nicely memaccess with the rest of the + * function. + * TODO: Use the fault error in PAR_EL1 to avoid pointless + * translation. + */ if ( par ) { + paddr_t ipa; + unsigned int s1_perms; + /* * When memaccess is enabled, the translation GVA to MADDR may * have failed because of a permission fault. @@ -1455,20 +1479,48 @@ struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t va, if ( p2m->mem_access_enabled ) return p2m_mem_access_check_and_get_page(va, flags, v); - dprintk(XENLOG_G_DEBUG, - "%pv: gvirt_to_maddr failed va=%#"PRIvaddr" flags=0x%lx par=%#"PRIx64"\n", - v, va, flags, par); - return NULL; - } + /* + * The software stage-1 table walk can still fail, e.g, if the + * GVA is not mapped. + */ + if ( !guest_walk_tables(v, va, &ipa, &s1_perms) ) + { + dprintk(XENLOG_G_DEBUG, + "%pv: Failed to walk page-table va %#"PRIvaddr"\n", v, va); + return NULL; + } - if ( !mfn_valid(maddr_to_mfn(maddr)) ) + mfn = p2m_lookup(d, gaddr_to_gfn(ipa), &t); + if ( mfn_eq(INVALID_MFN, mfn) || !p2m_is_ram(t) ) + return NULL; + + /* + * Check permission that are assumed by the caller. For instance + * in case of guestcopy, the caller assumes that the translated + * page can be accessed with the requested permissions. If this + * is not the case, we should fail. + * + * Please note that we do not check for the GV2M_EXEC + * permission. This is fine because the hardware-based translation + * instruction does not test for execute permissions. + */ + if ( (flags & GV2M_WRITE) && !(s1_perms & GV2M_WRITE) ) + return NULL; + + if ( (flags & GV2M_WRITE) && t != p2m_ram_rw ) + return NULL; + } + else + mfn = maddr_to_mfn(maddr); + + if ( !mfn_valid(mfn) ) { dprintk(XENLOG_G_DEBUG, "%pv: Invalid MFN %#"PRI_mfn"\n", - v, mfn_x(maddr_to_mfn(maddr))); + v, mfn_x(mfn)); return NULL; } - page = mfn_to_page(maddr_to_mfn(maddr)); + page = mfn_to_page(mfn); ASSERT(page); if ( unlikely(!get_page(page, d)) )