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SubjectRe: [PATCH 1/1] x86/iommu: fix incorrect bit operations in setting values
The kdump starts 2nd kernel without any error message when I use
3.18.0-rc4 merged last 6 patchs. The following is the message which 2nd
kernel prints during booting.

Patchset:
0001-iommu-vt-d-Update-iommu_attach_domain-and-its-caller.patch
0002-iommu-vt-d-Items-required-for-kdump.patch
0003-iommu-vt-d-data-types-and-functions-used-for-kdump.patch
0004-iommu-vt-d-Add-domain-id-functions.patch
0005-iommu-vt-d-enable-kdump-support-in-iommu-module.patch
0006-x86-iommu-fix-incorrect-bit-operations-in-setting-va.patch

log:
[ 1.689604] IOMMU intel_iommu_in_crashdump = true
[ 1.694310] IOMMU Skip disabling iommu hardware translations
[ 1.699987] DMAR: No ATSR found
[ 1.703151] IOMMU Copying translate tables from panicked kernel
[ 1.710786] IOMMU: root_new_virt:0xffff8800296ec000 phys:0x0000296ec000
[ 1.717401] IOMMU:0 Domain ids from panicked kernel:
[ 1.722364] DID did:13(0x000d)
[ 1.725424] DID did:12(0x000c)
[ 1.728482] DID did:11(0x000b)
[ 1.731542] DID did:10(0x000a)
[ 1.734603] DID did:6(0x0006)
[ 1.737574] DID did:7(0x0007)
[ 1.740549] DID did:5(0x0005)
[ 1.743522] DID did:9(0x0009)
[ 1.746495] DID did:8(0x0008)
[ 1.749467] DID did:4(0x0004)
[ 1.752439] DID did:3(0x0003)
[ 1.755413] DID did:2(0x0002)
[ 1.758385] DID did:0(0x0000)
[ 1.761357] DID did:1(0x0001)
[ 1.764331] ----------------------------------------
[ 1.769302] IOMMU 0 0xfed50000: using Queued invalidation

On 11/05/14 at 03:30pm, Li, Zhen-Hua wrote:
> The function context_set_address_root() and set_root_value are setting new
> address in a wrong way, and this patch is trying to fix this problem.
>
> According to Intel Vt-d specs(Feb 2011, Revision 1.3), Chapter 9.1 and 9.2,
> field ctp in root entry is using bits 12:63, field asr in context entry is
> using bits 12:63.
>
> To set these fields, the following functions are used:
> static inline void context_set_address_root(struct context_entry *context,
> unsigned long value);
> and
> static inline void set_root_value(struct root_entry *root, unsigned long value)
>
> But they are using an invalid method to set these fields, in current code, only
> a '|' operator is used to set it. This will not set the asr to the expected
> value if it has an old value.
>
> For example:
> Before calling this function,
> context->lo = 0x3456789012111;
> value = 0x123456789abcef12;
>
> After we call context_set_address_root(context, value), expected result is
> context->lo == 0x123456789abce111;
>
> But the actual result is:
> context->lo == 0x1237577f9bbde111;
>
> So we need to clear bits 12:63 before setting the new value, this will fix
> this problem.
>
> Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
> ---
> drivers/iommu/intel-iommu.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index a27d6cb..11ac47b 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -195,6 +195,7 @@ static inline void set_root_present(struct root_entry *root)
> }
> static inline void set_root_value(struct root_entry *root, unsigned long value)
> {
> + root->val &= ~VTD_PAGE_MASK;
> root->val |= value & VTD_PAGE_MASK;
> }
>
> @@ -247,6 +248,7 @@ static inline void context_set_translation_type(struct context_entry *context,
> static inline void context_set_address_root(struct context_entry *context,
> unsigned long value)
> {
> + context->lo &= ~VTD_PAGE_MASK;
> context->lo |= value & VTD_PAGE_MASK;
> }
>
> --
> 2.0.0-rc0
>
> --
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