diff options
| author | FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> | 2009-11-10 19:46:20 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-11-10 12:32:07 +0100 |
| commit | 75f1cdf1dda92cae037ec848ae63690d91913eac (patch) | |
| tree | 9c12705002ebfa2d75333c20a19d0ac15f1db1d9 /drivers/pci | |
| parent | ad32e8cb86e7894aac51c8963eaa9f36bb8a4e14 (diff) | |
x86: Handle HW IOMMU initialization failure gracefully
If HW IOMMU initialization fails (Intel VT-d often does this,
typically due to BIOS bugs), we fall back to nommu. It doesn't
work for the majority since nowadays we have more than 4GB
memory so we must use swiotlb instead of nommu.
The problem is that it's too late to initialize swiotlb when HW
IOMMU initialization fails. We need to allocate swiotlb memory
earlier from bootmem allocator. Chris explained the issue in
detail:
http://marc.info/?l=linux-kernel&m=125657444317079&w=2
The current x86 IOMMU initialization sequence is too complicated
and handling the above issue makes it more hacky.
This patch changes x86 IOMMU initialization sequence to handle
the above issue cleanly.
The new x86 IOMMU initialization sequence are:
1. we initialize the swiotlb (and setting swiotlb to 1) in the case
of (max_pfn > MAX_DMA32_PFN && !no_iommu). dma_ops is set to
swiotlb_dma_ops or nommu_dma_ops. if swiotlb usage is forced by
the boot option, we finish here.
2. we call the detection functions of all the IOMMUs
3. the detection function sets x86_init.iommu.iommu_init to the
IOMMU initialization function (so we can avoid calling the
initialization functions of all the IOMMUs needlessly).
4. if the IOMMU initialization function doesn't need to swiotlb
then sets swiotlb to zero (e.g. the initialization is
sucessful).
5. if we find that swiotlb is set to zero, we free swiotlb
resource.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: chrisw@sous-sol.org
Cc: dwmw2@infradead.org
Cc: joerg.roedel@amd.com
Cc: muli@il.ibm.com
LKML-Reference: <1257849980-22640-10-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/dmar.c | 3 | ||||
| -rw-r--r-- | drivers/pci/intel-iommu.c | 6 |
2 files changed, 5 insertions, 4 deletions
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c index bce9cd7c755..437399667e5 100644 --- a/drivers/pci/dmar.c +++ b/drivers/pci/dmar.c @@ -613,8 +613,7 @@ void __init detect_intel_iommu(void) "x2apic and Intr-remapping.\n"); #endif #ifdef CONFIG_DMAR - if (ret && !no_iommu && !iommu_detected && !swiotlb && - !dmar_disabled) + if (ret && !no_iommu && !iommu_detected && !dmar_disabled) iommu_detected = 1; #endif #ifdef CONFIG_X86 diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index b1e97e68250..43d755a2e14 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -3231,7 +3231,7 @@ int __init intel_iommu_init(void) * Check the need for DMA-remapping initialization now. * Above initialization will also be used by Interrupt-remapping. */ - if (no_iommu || swiotlb || dmar_disabled) + if (no_iommu || dmar_disabled) return -ENODEV; iommu_init_mempool(); @@ -3252,7 +3252,9 @@ int __init intel_iommu_init(void) "PCI-DMA: Intel(R) Virtualization Technology for Directed I/O\n"); init_timer(&unmap_timer); - force_iommu = 1; +#ifdef CONFIG_SWIOTLB + swiotlb = 0; +#endif dma_ops = &intel_dma_ops; init_iommu_sysfs(); |