From: Roger Pau Monné <roger.pau@citrix.com>
Date: Fri, 10 Feb 2017 09:40:29 +0000 (+0100)
Subject: x86/acpi: fix unmapping of low 1MB memory in acpi_os_unmap_memory
X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~2823
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=1f32b0291e98217d6a802e0ee30acb1a4929f84a;p=xen.git

x86/acpi: fix unmapping of low 1MB memory in acpi_os_unmap_memory

Current code in acpi_os_map_memory uses the direct map in order to map memory
in the low 1MB, but acpi_os_unmap_memory doesn't takes that into account, and
always tries to perform a vunmap, which results in the following WARN:

(XEN) Xen WARN at vmap.c:185
(XEN) ----[ Xen-4.9-unstable  x86_64  debug=y   Tainted:  C   ]----
(XEN) CPU:    0
(XEN) RIP:    e008:[<ffff82d0801369d7>] vmap.c#vm_free+0xd7/0xe0
[...]
(XEN) Xen call trace:
(XEN)    [<ffff82d0801369d7>] vmap.c#vm_free+0xd7/0xe0
(XEN)    [<ffff82d0802bdeda>] acpi_find_root_pointer+0x3a/0x170
(XEN)    [<ffff82d0802bd0ee>] acpi_os_get_root_pointer+0x4e/0x60
(XEN)    [<ffff82d0802d74d0>] domain_build.c#pvh_setup_acpi_xsdt+0x90/0x240
(XEN)    [<ffff82d0802d5d1a>] domain_build.c#pvh_setup_acpi+0x18a/0x2e0
(XEN)    [<ffff82d0802d3ad2>] domain_build.c#construct_dom0_pvh+0xd2/0x120
(XEN)    [<ffff82d0802c9174>] __start_xen+0x1d14/0x2420
(XEN)    [<ffff82d080100073>] __high_start+0x53/0x60

Fix this by checking if the virtual address passed to acpi_os_unmap_memory
belongs to the direct map.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/drivers/acpi/osl.c b/xen/drivers/acpi/osl.c
index 7199047198..930e2d9afb 100644
--- a/xen/drivers/acpi/osl.c
+++ b/xen/drivers/acpi/osl.c
@@ -104,6 +104,13 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 
 void acpi_os_unmap_memory(void __iomem * virt, acpi_size size)
 {
+	if (IS_ENABLED(CONFIG_X86) &&
+	    (unsigned long)virt >= DIRECTMAP_VIRT_START &&
+	    (unsigned long)virt < DIRECTMAP_VIRT_END) {
+		ASSERT(!((__pa(virt) + size - 1) >> 20));
+		return;
+	}
+
 	if (system_state >= SYS_STATE_boot)
 		vunmap((void *)((unsigned long)virt & PAGE_MASK));
 }