[Xen-changelog] [xen master] x86/acpi: fix unmapping of low 1MB memory in acpi_os_unmap_memory

[patchbot@xxxxxxx]

commit 1f32b0291e98217d6a802e0ee30acb1a4929f84a
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Fri Feb 10 10:40:29 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Feb 10 10:40:29 2017 +0100

    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@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/drivers/acpi/osl.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/xen/drivers/acpi/osl.c b/xen/drivers/acpi/osl.c
index 7199047..930e2d9 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));
 }
--
generated by git-patchbot for /home/xen/git/xen.git#master

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