From 2fe1339ea26bb7ba59e844b5c1dee03250a7de16 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Sat, 20 Feb 2016 13:37:04 +0000
Subject: [PATCH] Some BIOSes ACPI bytecode needs to take (sleepable) acpi
 mutex for acpi_GetInteger() execution.  Intel DMAR interrupt remapping code
 needs to know UID of the HPET to properly route the FSB interrupts from the
 HPET, even when interrupt remapping is disabled, and the code is executed
 under some non-sleepable mutexes.

Cache HPET UIDs in the device softc at the attach time and provide
lock-less method to get UID, use the method from the dmar hpet
handling code instead of calling GetInteger().

Reported and tested by:	Larry Rosenman <ler@lerctr.org>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
---
 sys/dev/acpica/acpi_hpet.c | 11 +++++++++++
 sys/dev/acpica/acpivar.h   |  2 ++
 sys/x86/iommu/intel_drv.c  |  8 ++------
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/sys/dev/acpica/acpi_hpet.c b/sys/dev/acpica/acpi_hpet.c
index de4436f2a20..76fbd5aba25 100644
--- a/sys/dev/acpica/acpi_hpet.c
+++ b/sys/dev/acpica/acpi_hpet.c
@@ -85,6 +85,7 @@ struct hpet_softc {
 	struct resource		*intr_res;
 	void			*intr_handle;
 	ACPI_HANDLE		handle;
+	uint32_t		acpi_uid;
 	uint64_t		freq;
 	uint32_t		caps;
 	struct timecounter	tc;
@@ -295,6 +296,15 @@ hpet_intr(void *arg)
 	return (FILTER_STRAY);
 }
 
+uint32_t
+hpet_get_uid(device_t dev)
+{
+	struct hpet_softc *sc;
+
+	sc = device_get_softc(dev);
+	return (sc->acpi_uid);
+}
+
 static ACPI_STATUS
 hpet_find(ACPI_HANDLE handle, UINT32 level, void *context,
     void **status)
@@ -746,6 +756,7 @@ hpet_attach(device_t dev)
 			maxhpetet++;
 		}
 	}
+	acpi_GetInteger(sc->handle, "_UID", &sc->acpi_uid);
 
 	make_dev_args_init(&mda);
 	mda.mda_devsw = &hpet_cdevsw;
diff --git a/sys/dev/acpica/acpivar.h b/sys/dev/acpica/acpivar.h
index 4f601c96fef..4df83d5bcd2 100644
--- a/sys/dev/acpica/acpivar.h
+++ b/sys/dev/acpica/acpivar.h
@@ -441,6 +441,8 @@ int		acpi_wakeup_machdep(struct acpi_softc *sc, int state,
 int		acpi_table_quirks(int *quirks);
 int		acpi_machdep_quirks(int *quirks);
 
+uint32_t	hpet_get_uid(device_t dev);
+
 /* Battery Abstraction. */
 struct acpi_battinfo;
 
diff --git a/sys/x86/iommu/intel_drv.c b/sys/x86/iommu/intel_drv.c
index 47588af1cb6..e5d7783658c 100644
--- a/sys/x86/iommu/intel_drv.c
+++ b/sys/x86/iommu/intel_drv.c
@@ -826,13 +826,9 @@ dmar_find_nonpci(u_int id, u_int entry_type, uint16_t *rid)
 struct dmar_unit *
 dmar_find_hpet(device_t dev, uint16_t *rid)
 {
-	ACPI_HANDLE handle;
-	uint32_t hpet_id;
 
-	handle = acpi_get_handle(dev);
-	if (ACPI_FAILURE(acpi_GetInteger(handle, "_UID", &hpet_id)))
-		return (NULL);
-	return (dmar_find_nonpci(hpet_id, ACPI_DMAR_SCOPE_TYPE_HPET, rid));
+	return (dmar_find_nonpci(hpet_get_uid(dev), ACPI_DMAR_SCOPE_TYPE_HPET,
+	    rid));
 }
 
 struct dmar_unit *