Merge tag 'for-linus-5.11-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:

 - A fix for a regression introduced in 5.11 resulting in Xen dom0
   having problems to correctly initialize Xenstore.

 - A fix for avoiding WARN splats when booting as Xen dom0 with
   CONFIG_AMD_MEM_ENCRYPT enabled due to a missing trap handler for the
   #VC exception (even if the handler should never be called).

 - A fix for the Xen bklfront driver adapting to the correct but
   unexpected behavior of new qemu.

* tag 'for-linus-5.11-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  x86/xen: avoid warning in Xen pv guest with CONFIG_AMD_MEM_ENCRYPT enabled
  xen: Fix XenStore initialisation for XS_LOCAL
  xen-blkfront: allow discard-* nodes to be optional

arch/x86/include/asm/idtentry.h

@@ -613,6 +613,7 @@ DECLARE_IDTENTRY_VC(X86_TRAP_VC,	exc_vmm_communication);
 
 #ifdef CONFIG_XEN_PV
 DECLARE_IDTENTRY_XENCB(X86_TRAP_OTHER,	exc_xen_hypervisor_callback);
+DECLARE_IDTENTRY_RAW(X86_TRAP_OTHER,	exc_xen_unknown_trap);
 #endif
 
 /* Device interrupts common/spurious */

arch/x86/xen/enlighten_pv.c

@@ -583,6 +583,13 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_debug)
 		exc_debug(regs);
 }
 
+DEFINE_IDTENTRY_RAW(exc_xen_unknown_trap)
+{
+	/* This should never happen and there is no way to handle it. */
+	pr_err("Unknown trap in Xen PV mode.");
+	BUG();
+}
+
 struct trap_array_entry {
 	void (*orig)(void);
 	void (*xen)(void);
@@ -631,6 +638,7 @@ static bool __ref get_trap_addr(void **addr, unsigned int ist)
 {
 	unsigned int nr;
 	bool ist_okay = false;
+	bool found = false;
 
 	/*
 	 * Replace trap handler addresses by Xen specific ones.
@@ -645,6 +653,7 @@ static bool __ref get_trap_addr(void **addr, unsigned int ist)
 		if (*addr == entry->orig) {
 			*addr = entry->xen;
 			ist_okay = entry->ist_okay;
+			found = true;
 			break;
 		}
 	}
@@ -655,9 +664,13 @@ static bool __ref get_trap_addr(void **addr, unsigned int ist)
 		nr = (*addr - (void *)early_idt_handler_array[0]) /
 		     EARLY_IDT_HANDLER_SIZE;
 		*addr = (void *)xen_early_idt_handler_array[nr];
+		found = true;
 	}
 
-	if (WARN_ON(ist != 0 && !ist_okay))
+	if (!found)
+		*addr = (void *)xen_asm_exc_xen_unknown_trap;
+
+	if (WARN_ON(found && ist != 0 && !ist_okay))
 		return false;
 
 	return true;

arch/x86/xen/xen-asm.S

@@ -178,6 +178,7 @@ xen_pv_trap asm_exc_simd_coprocessor_error
 #ifdef CONFIG_IA32_EMULATION
 xen_pv_trap entry_INT80_compat
 #endif
+xen_pv_trap asm_exc_xen_unknown_trap
 xen_pv_trap asm_exc_xen_hypervisor_callback
 
 	__INIT

drivers/block/xen-blkfront.c

@@ -945,7 +945,8 @@ static void blkif_set_queue_limits(struct blkfront_info *info)
 	if (info->feature_discard) {
 		blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
 		blk_queue_max_discard_sectors(rq, get_capacity(gd));
-		rq->limits.discard_granularity = info->discard_granularity;
+		rq->limits.discard_granularity = info->discard_granularity ?:
+						 info->physical_sector_size;
 		rq->limits.discard_alignment = info->discard_alignment;
 		if (info->feature_secdiscard)
 			blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
@@ -2179,19 +2180,12 @@ static void blkfront_closing(struct blkfront_info *info)
 
 static void blkfront_setup_discard(struct blkfront_info *info)
 {
-	int err;
-	unsigned int discard_granularity;
-	unsigned int discard_alignment;
-
 	info->feature_discard = 1;
-	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-		"discard-granularity", "%u", &discard_granularity,
-		"discard-alignment", "%u", &discard_alignment,
-		NULL);
-	if (!err) {
-		info->discard_granularity = discard_granularity;
-		info->discard_alignment = discard_alignment;
-	}
+	info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
+							 "discard-granularity",
+							 0);
+	info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
+						       "discard-alignment", 0);
 	info->feature_secdiscard =
 		!!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
 				       0);

drivers/xen/xenbus/xenbus_probe.c

@@ -714,6 +714,23 @@ static bool xs_hvm_defer_init_for_callback(void)
 #endif
 }
 
+static int xenbus_probe_thread(void *unused)
+{
+	DEFINE_WAIT(w);
+
+	/*
+	 * We actually just want to wait for *any* trigger of xb_waitq,
+	 * and run xenbus_probe() the moment it occurs.
+	 */
+	prepare_to_wait(&xb_waitq, &w, TASK_INTERRUPTIBLE);
+	schedule();
+	finish_wait(&xb_waitq, &w);
+
+	DPRINTK("probing");
+	xenbus_probe();
+	return 0;
+}
+
 static int __init xenbus_probe_initcall(void)
 {
 	/*
@@ -725,6 +742,20 @@ static int __init xenbus_probe_initcall(void)
 	     !xs_hvm_defer_init_for_callback()))
 		xenbus_probe();
 
+	/*
+	 * For XS_LOCAL, spawn a thread which will wait for xenstored
+	 * or a xenstore-stubdom to be started, then probe. It will be
+	 * triggered when communication starts happening, by waiting
+	 * on xb_waitq.
+	 */
+	if (xen_store_domain_type == XS_LOCAL) {
+		struct task_struct *probe_task;
+
+		probe_task = kthread_run(xenbus_probe_thread, NULL,
+					 "xenbus_probe");
+		if (IS_ERR(probe_task))
+			return PTR_ERR(probe_task);
+	}
 	return 0;
 }
 device_initcall(xenbus_probe_initcall);