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author | Jan Beulich <jbeulich@suse.com> | 2012-11-02 17:15:30 +0100 |
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committer | Jan Beulich <jbeulich@suse.com> | 2012-11-02 17:15:30 +0100 |
commit | 7a8f6d0607a38c64506b4e8b473d955bf8e2a71f (patch) | |
tree | addc701cdee69b8f8a0e49d5376af13bfce58f84 /xen/include/xen/iommu.h | |
parent | cfba0545007fd18659917d8ec5ebde044cd9418b (diff) | |
download | xen-7a8f6d0607a38c64506b4e8b473d955bf8e2a71f.tar.gz xen-7a8f6d0607a38c64506b4e8b473d955bf8e2a71f.tar.bz2 xen-7a8f6d0607a38c64506b4e8b473d955bf8e2a71f.zip |
IOMMU: keep disabled until iommu_setup() is called
The iommu is enabled by default when xen is booting and later disabled
in iommu_setup() when no iommu is present.
But under some circumstances iommu code can be called before
iommu_setup() is processed. If there is no iommu available xen crashes.
This can happen for example when panic(...) is called as introduced
with the patch "x86-64: detect processors subject to AMD erratum #121
and refuse to boot" since xen 4.1.3, resulting in
find_iommu_for_device() to be called in the context of
disable_IO_APIC() / __stop_this_cpu().
This patch fixes this by keeping the iommu disabled until iommu_setup()
is entered.
Originally-by: Ronny Hegewald <ronny.hegewald@online.de>
In order for iommu_enable to be off initially, iommu_supports_eim()
must not depend on it anymore, nor must acpi_parse_dmar(). The former
in turn requires that iommu_intremap gets uncoupled from iommu_enabled
(in particular, failure during IOMMU setup should no longer result in
iommu_intremap getting cleared by generic code; IOMMU specific code
can still do so provided in can live with the consequences).
This could have the nice side effect of allowing to use "iommu=off"
even when x2APIC was pre-enabled by the BIOS (in which case interrupt
remapping is a requirement, but DMA translation [obviously] isn't), but
that doesn't currently work (and hence x2apic_bsp_setup() forces the
IOMMU on rather than just interrupt remapping).
For consistency with VT-d, make the AMD IOMMU code also skip all ACPI
table parsing when neither iommu_enable nor iommu_intremap are set.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
Acked-by: "Huang2, Wei" <Wei.Huang2@amd.com>
Diffstat (limited to 'xen/include/xen/iommu.h')
-rw-r--r-- | xen/include/xen/iommu.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h index 88420a5fce..3026e54606 100644 --- a/xen/include/xen/iommu.h +++ b/xen/include/xen/iommu.h @@ -26,7 +26,7 @@ #include <public/hvm/ioreq.h> #include <public/domctl.h> -extern bool_t iommu_enabled; +extern bool_t iommu_enable, iommu_enabled; extern bool_t force_iommu, iommu_verbose; extern bool_t iommu_workaround_bios_bug, iommu_passthrough; extern bool_t iommu_snoop, iommu_qinval, iommu_intremap; |