Messages in this thread Patch in this message | | | Subject | Re: [PATCH] iommu/vt-d: avoid unnecessory panic if iommu init fail in tboot | From | Lu Baolu <> | Date | Mon, 9 Nov 2020 11:08:17 +0800 |
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Hi Zhenzhong,
On 11/9/20 10:27 AM, Zhenzhong Duan wrote: > +intel iommu maintainers, > > Can anyone help review this patch? Thanks > > Zhenzhong > > On Wed, Nov 4, 2020 at 4:15 PM Zhenzhong Duan <zhenzhong.duan@gmail.com> wrote: >> >> "intel_iommu=off" command line is used to disable iommu and iommu is force >> enabled in a tboot system. Meanwhile "intel_iommu=tboot_noforce,off" >> could be used to force disable iommu in tboot for better performance. >> >> By default kernel should panic if iommu init fail in tboot for security >> reason, but it's unnecessory if we use "intel_iommu=tboot_noforce,off". >> >> Fix it by return 0 in tboot_force_iommu() so that force_on is not set. >> >> Fixes: 7304e8f28bb2 ("iommu/vt-d: Correctly disable Intel IOMMU force on") >> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com> >> --- >> arch/x86/kernel/tboot.c | 5 +---- >> 1 file changed, 1 insertion(+), 4 deletions(-) >> >> diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c >> index 992fb1415c0f..9fd4d162b331 100644 >> --- a/arch/x86/kernel/tboot.c >> +++ b/arch/x86/kernel/tboot.c >> @@ -511,12 +511,9 @@ struct acpi_table_header *tboot_get_dmar_table(struct acpi_table_header *dmar_tb >> >> int tboot_force_iommu(void) >> { >> - if (!tboot_enabled()) >> + if (!tboot_enabled() || intel_iommu_tboot_noforce) >> return 0; >> >> - if (intel_iommu_tboot_noforce) >> - return 1;
This was obviously wrong. It should return false, right?
It looks odd that intel_iommu_tboot_noforce is defined in Intel iommu implementation, but is used here. How about moving it back to the iommu driver?
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c index 992fb1415c0f..420be871d9d4 100644 --- a/arch/x86/kernel/tboot.c +++ b/arch/x86/kernel/tboot.c @@ -514,9 +514,6 @@ int tboot_force_iommu(void) if (!tboot_enabled()) return 0;
- if (intel_iommu_tboot_noforce) - return 1; - if (no_iommu || swiotlb || dmar_disabled) pr_warn("Forcing Intel-IOMMU to enabled\n");
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index a41f9f13cc86..ba90eb4325d0 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -179,7 +179,7 @@ static int rwbf_quirk; * (used when kernel is launched w/ TXT) */ static int force_on = 0; -int intel_iommu_tboot_noforce; +static int intel_iommu_tboot_noforce; static int no_platform_optin;
#define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry)) @@ -4212,7 +4212,8 @@ int __init intel_iommu_init(void) * Intel IOMMU is required for a TXT/tboot launch or platform * opt in, so enforce that. */ - force_on = tboot_force_iommu() || platform_optin_force_iommu(); + force_on = (!intel_iommu_tboot_noforce && tboot_force_iommu()) || + platform_optin_force_iommu();
if (iommu_init_mempool()) { if (force_on) diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h index fbf5b3e7707e..d956987ed032 100644 --- a/include/linux/intel-iommu.h +++ b/include/linux/intel-iommu.h @@ -798,7 +798,6 @@ extern int iommu_calculate_agaw(struct intel_iommu *iommu); extern int iommu_calculate_max_sagaw(struct intel_iommu *iommu); extern int dmar_disabled; extern int intel_iommu_enabled; -extern int intel_iommu_tboot_noforce; extern int intel_iommu_gfx_mapped; #else static inline int iommu_calculate_agaw(struct intel_iommu *iommu) >> - >> if (no_iommu || swiotlb || dmar_disabled) >> pr_warn("Forcing Intel-IOMMU to enabled\n"); >> >> -- >> 2.25.1 >>
Best regards, baolu
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