diff options
Diffstat (limited to 'system/xen/xsa/xsa243.patch')
| -rw-r--r-- | system/xen/xsa/xsa243.patch | 93 |
1 files changed, 0 insertions, 93 deletions
diff --git a/system/xen/xsa/xsa243.patch b/system/xen/xsa/xsa243.patch deleted file mode 100644 index aaff277514dc9..0000000000000 --- a/system/xen/xsa/xsa243.patch +++ /dev/null @@ -1,93 +0,0 @@ -From: Andrew Cooper <andrew.cooper3@citrix.com> -Subject: x86/shadow: Don't create self-linear shadow mappings for 4-level translated guests - -When initially creating a monitor table for 4-level translated guests, don't -install a shadow-linear mapping. This mapping is actually self-linear, and -trips up the writeable heuristic logic into following Xen's mappings, not the -guests' shadows it was expecting to follow. - -A consequence of this is that sh_guess_wrmap() needs to cope with there being -no shadow-linear mapping present, which in practice occurs once each time a -vcpu switches to 4-level paging from a different paging mode. - -An appropriate shadow-linear slot will be inserted into the monitor table -either while constructing lower level monitor tables, or by sh_update_cr3(). - -While fixing this, clarify the safety of the other mappings. Despite -appearing unsafe, it is correct to create a guest-linear mapping for -translated domains; this is self-linear and doesn't point into the translated -domain. Drop a dead clause for translate != external guests. - -This is XSA-243. - -Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> -Acked-by: Tim Deegan <tim@xen.org> - -diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c -index 8d4f244..a18d286 100644 ---- a/xen/arch/x86/mm/shadow/multi.c -+++ b/xen/arch/x86/mm/shadow/multi.c -@@ -1485,26 +1485,38 @@ void sh_install_xen_entries_in_l4(struct domain *d, mfn_t gl4mfn, mfn_t sl4mfn) - sl4e[shadow_l4_table_offset(RO_MPT_VIRT_START)] = shadow_l4e_empty(); - } - -- /* Shadow linear mapping for 4-level shadows. N.B. for 3-level -- * shadows on 64-bit xen, this linear mapping is later replaced by the -- * monitor pagetable structure, which is built in make_monitor_table -- * and maintained by sh_update_linear_entries. */ -- sl4e[shadow_l4_table_offset(SH_LINEAR_PT_VIRT_START)] = -- shadow_l4e_from_mfn(sl4mfn, __PAGE_HYPERVISOR_RW); -- -- /* Self linear mapping. */ -- if ( shadow_mode_translate(d) && !shadow_mode_external(d) ) -+ /* -+ * Linear mapping slots: -+ * -+ * Calling this function with gl4mfn == sl4mfn is used to construct a -+ * monitor table for translated domains. In this case, gl4mfn forms the -+ * self-linear mapping (i.e. not pointing into the translated domain), and -+ * the shadow-linear slot is skipped. The shadow-linear slot is either -+ * filled when constructing lower level monitor tables, or via -+ * sh_update_cr3() for 4-level guests. -+ * -+ * Calling this function with gl4mfn != sl4mfn is used for non-translated -+ * guests, where the shadow-linear slot is actually self-linear, and the -+ * guest-linear slot points into the guests view of its pagetables. -+ */ -+ if ( shadow_mode_translate(d) ) - { -- // linear tables may not be used with translated PV guests -- sl4e[shadow_l4_table_offset(LINEAR_PT_VIRT_START)] = -+ ASSERT(mfn_eq(gl4mfn, sl4mfn)); -+ -+ sl4e[shadow_l4_table_offset(SH_LINEAR_PT_VIRT_START)] = - shadow_l4e_empty(); - } - else - { -- sl4e[shadow_l4_table_offset(LINEAR_PT_VIRT_START)] = -- shadow_l4e_from_mfn(gl4mfn, __PAGE_HYPERVISOR_RW); -+ ASSERT(!mfn_eq(gl4mfn, sl4mfn)); -+ -+ sl4e[shadow_l4_table_offset(SH_LINEAR_PT_VIRT_START)] = -+ shadow_l4e_from_mfn(sl4mfn, __PAGE_HYPERVISOR_RW); - } - -+ sl4e[shadow_l4_table_offset(LINEAR_PT_VIRT_START)] = -+ shadow_l4e_from_mfn(gl4mfn, __PAGE_HYPERVISOR_RW); -+ - unmap_domain_page(sl4e); - } - #endif -@@ -4405,6 +4417,11 @@ static int sh_guess_wrmap(struct vcpu *v, unsigned long vaddr, mfn_t gmfn) - - /* Carefully look in the shadow linear map for the l1e we expect */ - #if SHADOW_PAGING_LEVELS >= 4 -+ /* Is a shadow linear map is installed in the first place? */ -+ sl4p = v->arch.paging.shadow.guest_vtable; -+ sl4p += shadow_l4_table_offset(SH_LINEAR_PT_VIRT_START); -+ if ( !(shadow_l4e_get_flags(*sl4p) & _PAGE_PRESENT) ) -+ return 0; - sl4p = sh_linear_l4_table(v) + shadow_l4_linear_offset(vaddr); - if ( !(shadow_l4e_get_flags(*sl4p) & _PAGE_PRESENT) ) - return 0; |