* Re: [PATCH] iommu/vt-d: avoid unnecessory panic if iommu init fail in tboot
[not found] <20201104081438.2075-1-zhenzhong.duan@gmail.com>
@ 2020-11-09 2:27 ` Zhenzhong Duan
2020-11-09 3:08 ` Lu Baolu
0 siblings, 1 reply; 3+ messages in thread
From: Zhenzhong Duan @ 2020-11-09 2:27 UTC (permalink / raw)
To: linux-kernel
Cc: jroedel, x86, iommu, ning.sun, tboot-devel, Ingo Molnar,
Borislav Petkov, Thomas Gleixner, David Woodhouse
+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;
> -
> if (no_iommu || swiotlb || dmar_disabled)
> pr_warn("Forcing Intel-IOMMU to enabled\n");
>
> --
> 2.25.1
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu/vt-d: avoid unnecessory panic if iommu init fail in tboot
2020-11-09 2:27 ` [PATCH] iommu/vt-d: avoid unnecessory panic if iommu init fail in tboot Zhenzhong Duan
@ 2020-11-09 3:08 ` Lu Baolu
2020-11-09 9:12 ` Zhenzhong Duan
0 siblings, 1 reply; 3+ messages in thread
From: Lu Baolu @ 2020-11-09 3:08 UTC (permalink / raw)
To: Zhenzhong Duan, linux-kernel
Cc: jroedel, x86, iommu, ning.sun, tboot-devel, Ingo Molnar,
Borislav Petkov, Thomas Gleixner, David Woodhouse
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
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu/vt-d: avoid unnecessory panic if iommu init fail in tboot
2020-11-09 3:08 ` Lu Baolu
@ 2020-11-09 9:12 ` Zhenzhong Duan
0 siblings, 0 replies; 3+ messages in thread
From: Zhenzhong Duan @ 2020-11-09 9:12 UTC (permalink / raw)
To: Lu Baolu
Cc: jroedel, x86, linux-kernel, iommu, ning.sun, tboot-devel,
Ingo Molnar, Borislav Petkov, Thomas Gleixner, David Woodhouse
Hi Baolu,
On Mon, Nov 9, 2020 at 11:15 AM Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
> 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?
I guess you missed above change: "if (!tboot_enabled() ||
intel_iommu_tboot_noforce)".
It does return false.
>
> 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?
That's better, will do. Thanks for your suggestion.
Zhenzhong
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-09 2:27 ` [PATCH] iommu/vt-d: avoid unnecessory panic if iommu init fail in tboot Zhenzhong Duan
2020-11-09 3:08 ` Lu Baolu
2020-11-09 9:12 ` Zhenzhong Duan
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