--- /dev/null
+From: Jan Beulich <jbeulich@suse.com>
+Date: Tue, 2 May 2017 12:18:35 +0100
+X-Dgit-Generated: 4.8.1-1+deb9u1 993a6534cae6d9ca2793799cfe369c9b3694ee1e
+Subject: multicall: deal with early exit conditions
+
+In particular changes to guest privilege level require the multicall
+sequence to be aborted, as hypercalls are permitted from kernel mode
+only. While likely not very useful in a multicall, also properly handle
+the return value in the HYPERVISOR_iret case (which should be the guest
+specified value).
+
+This is XSA-213.
+
+Reported-by: Jann Horn <jannh@google.com>
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
+Acked-by: Julien Grall <julien.grall@arm.com>
+
+---
+
+--- xen-4.8.1.orig/xen/arch/arm/traps.c
++++ xen-4.8.1/xen/arch/arm/traps.c
+@@ -1531,7 +1531,7 @@ static bool_t check_multicall_32bit_clea
+ return true;
+ }
+
+-void arch_do_multicall_call(struct mc_state *state)
++enum mc_disposition arch_do_multicall_call(struct mc_state *state)
+ {
+ struct multicall_entry *multi = &state->call;
+ arm_hypercall_fn_t call = NULL;
+@@ -1539,23 +1539,26 @@ void arch_do_multicall_call(struct mc_st
+ if ( multi->op >= ARRAY_SIZE(arm_hypercall_table) )
+ {
+ multi->result = -ENOSYS;
+- return;
++ return mc_continue;
+ }
+
+ call = arm_hypercall_table[multi->op].fn;
+ if ( call == NULL )
+ {
+ multi->result = -ENOSYS;
+- return;
++ return mc_continue;
+ }
+
+ if ( is_32bit_domain(current->domain) &&
+ !check_multicall_32bit_clean(multi) )
+- return;
++ return mc_continue;
+
+ multi->result = call(multi->args[0], multi->args[1],
+ multi->args[2], multi->args[3],
+ multi->args[4]);
++
++ return likely(!psr_mode_is_user(guest_cpu_user_regs()))
++ ? mc_continue : mc_preempt;
+ }
+
+ /*
+--- xen-4.8.1.orig/xen/arch/x86/hypercall.c
++++ xen-4.8.1/xen/arch/x86/hypercall.c
+@@ -255,15 +255,19 @@ void pv_hypercall(struct cpu_user_regs *
+ perfc_incr(hypercalls);
+ }
+
+-void arch_do_multicall_call(struct mc_state *state)
++enum mc_disposition arch_do_multicall_call(struct mc_state *state)
+ {
+- if ( !is_pv_32bit_vcpu(current) )
++ struct vcpu *curr = current;
++ unsigned long op;
++
++ if ( !is_pv_32bit_vcpu(curr) )
+ {
+ struct multicall_entry *call = &state->call;
+
+- if ( (call->op < ARRAY_SIZE(pv_hypercall_table)) &&
+- pv_hypercall_table[call->op].native )
+- call->result = pv_hypercall_table[call->op].native(
++ op = call->op;
++ if ( (op < ARRAY_SIZE(pv_hypercall_table)) &&
++ pv_hypercall_table[op].native )
++ call->result = pv_hypercall_table[op].native(
+ call->args[0], call->args[1], call->args[2],
+ call->args[3], call->args[4], call->args[5]);
+ else
+@@ -274,15 +278,21 @@ void arch_do_multicall_call(struct mc_st
+ {
+ struct compat_multicall_entry *call = &state->compat_call;
+
+- if ( (call->op < ARRAY_SIZE(pv_hypercall_table)) &&
+- pv_hypercall_table[call->op].compat )
+- call->result = pv_hypercall_table[call->op].compat(
++ op = call->op;
++ if ( (op < ARRAY_SIZE(pv_hypercall_table)) &&
++ pv_hypercall_table[op].compat )
++ call->result = pv_hypercall_table[op].compat(
+ call->args[0], call->args[1], call->args[2],
+ call->args[3], call->args[4], call->args[5]);
+ else
+ call->result = -ENOSYS;
+ }
+ #endif
++
++ return unlikely(op == __HYPERVISOR_iret)
++ ? mc_exit
++ : likely(guest_kernel_mode(curr, guest_cpu_user_regs()))
++ ? mc_continue : mc_preempt;
+ }
+
+ /*
+--- xen-4.8.1.orig/xen/common/multicall.c
++++ xen-4.8.1/xen/common/multicall.c
+@@ -40,6 +40,7 @@ do_multicall(
+ struct mc_state *mcs = ¤t->mc_state;
+ uint32_t i;
+ int rc = 0;
++ enum mc_disposition disp = mc_continue;
+
+ if ( unlikely(__test_and_set_bit(_MCSF_in_multicall, &mcs->flags)) )
+ {
+@@ -50,7 +51,7 @@ do_multicall(
+ if ( unlikely(!guest_handle_okay(call_list, nr_calls)) )
+ rc = -EFAULT;
+
+- for ( i = 0; !rc && i < nr_calls; i++ )
++ for ( i = 0; !rc && disp == mc_continue && i < nr_calls; i++ )
+ {
+ if ( i && hypercall_preempt_check() )
+ goto preempted;
+@@ -63,7 +64,7 @@ do_multicall(
+
+ trace_multicall_call(&mcs->call);
+
+- arch_do_multicall_call(mcs);
++ disp = arch_do_multicall_call(mcs);
+
+ #ifndef NDEBUG
+ {
+@@ -77,7 +78,14 @@ do_multicall(
+ }
+ #endif
+
+- if ( unlikely(__copy_field_to_guest(call_list, &mcs->call, result)) )
++ if ( unlikely(disp == mc_exit) )
++ {
++ if ( __copy_field_to_guest(call_list, &mcs->call, result) )
++ /* nothing, best effort only */;
++ rc = mcs->call.result;
++ }
++ else if ( unlikely(__copy_field_to_guest(call_list, &mcs->call,
++ result)) )
+ rc = -EFAULT;
+ else if ( mcs->flags & MCSF_call_preempted )
+ {
+@@ -93,6 +101,9 @@ do_multicall(
+ guest_handle_add_offset(call_list, 1);
+ }
+
++ if ( unlikely(disp == mc_preempt) && i < nr_calls )
++ goto preempted;
++
+ perfc_incr(calls_to_multicall);
+ perfc_add(calls_from_multicall, i);
+ mcs->flags = 0;
+--- xen-4.8.1.orig/xen/include/xen/multicall.h
++++ xen-4.8.1/xen/include/xen/multicall.h
+@@ -24,6 +24,10 @@ struct mc_state {
+ };
+ };
+
+-void arch_do_multicall_call(struct mc_state *mc);
++enum mc_disposition {
++ mc_continue,
++ mc_exit,
++ mc_preempt,
++} arch_do_multicall_call(struct mc_state *mc);
+
+ #endif /* __XEN_MULTICALL_H__ */
--- /dev/null
+From: Jan Beulich <jbeulich@suse.com>
+Date: Tue, 2 May 2017 12:18:38 +0100
+X-Dgit-Generated: 4.8.1-1+deb9u1 8733567025e5095d178d6d294dbf0405d2250e37
+Subject: x86: discard type information when stealing pages
+
+While a page having just a single general reference left necessarily
+has a zero type reference count too, its type may still be valid (and
+in validated state; at present this is only possible and relevant for
+PGT_seg_desc_page, as page tables have their type forcibly zapped when
+their type reference count drops to zero, and
+PGT_{writable,shared}_page pages don't require any validation). In
+such a case when the page is being re-used with the same type again,
+validation is being skipped. As validation criteria differ between
+32- and 64-bit guests, pages to be transferred between guests need to
+have their validation indicator zapped (and with it we zap all other
+type information at once).
+
+This is XSA-214.
+
+Reported-by: Jann Horn <jannh@google.com>
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
+
+---
+
+--- xen-4.8.1.orig/xen/arch/x86/mm.c
++++ xen-4.8.1/xen/arch/x86/mm.c
+@@ -4422,6 +4422,17 @@ int steal_page(
+ y = cmpxchg(&page->count_info, x, x & ~PGC_count_mask);
+ } while ( y != x );
+
++ /*
++ * With the sole reference dropped temporarily, no-one can update type
++ * information. Type count also needs to be zero in this case, but e.g.
++ * PGT_seg_desc_page may still have PGT_validated set, which we need to
++ * clear before transferring ownership (as validation criteria vary
++ * depending on domain type).
++ */
++ BUG_ON(page->u.inuse.type_info & (PGT_count_mask | PGT_locked |
++ PGT_pinned));
++ page->u.inuse.type_info = 0;
++
+ /* Swizzle the owner then reinstate the PGC_allocated reference. */
+ page_set_owner(page, NULL);
+ y = page->count_info;
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