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iommu/vt-d: Turn off translations at shutdown 

The intel-iommu driver assumes that the iommu state is
cleaned up at the start of the new kernel.
But, when we try to kexec boot something other than the
Linux kernel, the cleanup cannot be relied upon.
Hence, cleanup before we go down for reboot.

Keeping the cleanup at initialization also, in case BIOS
leaves the IOMMU enabled.

I considered turning off iommu only during kexec reboot, but a clean
shutdown seems always a good idea. But if someone wants to make it
conditional, such as VMM live update, we can do that.  There doesn't
seem to be such a condition at this time.

Tested that before, the info message
'DMAR: Translation was enabled for <iommu> but we are not in kdump mode'
would be reported for each iommu. The message will not appear when the
DMA-remapping is not enabled on entry to the kernel.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Deepa Dinamani 2019-11-10 09:27:44 -08:00 committed by Joerg Roedel
parent f036c7fa0a
commit 6c3a44ed3c
3 changed files with 26 additions and 1 deletions
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5
drivers/iommu/dmar.c
View File

@ -895,8 +895,11 @@ int __init detect_intel_iommu(void)
}
#ifdef CONFIG_X86
if (!ret)
if (!ret) {
x86_init.iommu.iommu_init = intel_iommu_init;
x86_platform.iommu_shutdown = intel_iommu_shutdown;
}
#endif
if (dmar_tbl) {

20
drivers/iommu/intel-iommu.c
View File

@ -4762,6 +4762,26 @@ static void intel_disable_iommus(void)
iommu_disable_translation(iommu);
}
void intel_iommu_shutdown(void)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu = NULL;
if (no_iommu || dmar_disabled)
return;
down_write(&dmar_global_lock);
/* Disable PMRs explicitly here. */
for_each_iommu(iommu, drhd)
iommu_disable_protect_mem_regions(iommu);
/* Make sure the IOMMUs are switched off */
intel_disable_iommus();
up_write(&dmar_global_lock);
}
static inline struct intel_iommu *dev_to_intel_iommu(struct device *dev)
{
struct iommu_device *iommu_dev = dev_to_iommu_device(dev);

2
include/linux/dmar.h
View File

@ -129,6 +129,7 @@ static inline int dmar_res_noop(struct acpi_dmar_header *hdr, void *arg)
#ifdef CONFIG_INTEL_IOMMU
extern int iommu_detected, no_iommu;
extern int intel_iommu_init(void);
extern void intel_iommu_shutdown(void);
extern int dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg);
extern int dmar_parse_one_atsr(struct acpi_dmar_header *header, void *arg);
extern int dmar_check_one_atsr(struct acpi_dmar_header *hdr, void *arg);
@ -137,6 +138,7 @@ extern int dmar_iommu_hotplug(struct dmar_drhd_unit *dmaru, bool insert);
extern int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info);
#else /* !CONFIG_INTEL_IOMMU: */
static inline int intel_iommu_init(void) { return -ENODEV; }
static inline void intel_iommu_shutdown(void) { }
#define dmar_parse_one_rmrr dmar_res_noop
#define dmar_parse_one_atsr dmar_res_noop