Re: [RFC PATCH 6/7] iommu/amd: Introduce amd_iommu_pgtable command-line option

2021-03-21 Thread Suravee Suthikulpanit 

Joerg,

On 3/18/21 10:33 PM, Joerg Roedel wrote:

On Fri, Mar 12, 2021 at 03:04:10AM -0600, Suravee Suthikulpanit wrote:

To allow specification whether to use v1 or v2 IOMMU pagetable for
DMA remapping when calling kernel DMA-API.

Signed-off-by: Suravee Suthikulpanit 
---
  Documentation/admin-guide/kernel-parameters.txt |  6 ++
  drivers/iommu/amd/init.c| 15 +++
  2 files changed, 21 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt 
b/Documentation/admin-guide/kernel-parameters.txt
index 04545725f187..466e807369ea 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -319,6 +319,12 @@
 This mode requires kvm-amd.avic=1.
 (Default when IOMMU HW support is present.)
  
+	amd_iommu_pgtable= [HW,X86-64]

+   Specifies one of the following AMD IOMMU page table to
+   be used for DMA remapping for DMA-API:
+   v1 - Use v1 page table (Default)
+   v2 - Use v2 page table


Any reason v2 can not be the default when it is supported by the IOMMU?



Eventually, we should be able to default to v2. However, we will need to make 
sure that
the v2 implementation will have comparable performance as currently used v1.

FYI: I'm also looking into adding support for SVA as well.

Thanks,
Suravee

Re: [RFC PATCH 6/7] iommu/amd: Introduce amd_iommu_pgtable command-line option

2021-03-18 Thread Joerg Roedel 
On Fri, Mar 12, 2021 at 03:04:10AM -0600, Suravee Suthikulpanit wrote:
> To allow specification whether to use v1 or v2 IOMMU pagetable for
> DMA remapping when calling kernel DMA-API.
> 
> Signed-off-by: Suravee Suthikulpanit 
> ---
>  Documentation/admin-guide/kernel-parameters.txt |  6 ++
>  drivers/iommu/amd/init.c| 15 +++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt 
> b/Documentation/admin-guide/kernel-parameters.txt
> index 04545725f187..466e807369ea 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -319,6 +319,12 @@
>This mode requires kvm-amd.avic=1.
>(Default when IOMMU HW support is present.)
>  
> + amd_iommu_pgtable= [HW,X86-64]
> + Specifies one of the following AMD IOMMU page table to
> + be used for DMA remapping for DMA-API:
> + v1 - Use v1 page table (Default)
> + v2 - Use v2 page table

Any reason v2 can not be the default when it is supported by the IOMMU?

[RFC PATCH 6/7] iommu/amd: Introduce amd_iommu_pgtable command-line option

2021-03-12 Thread Suravee Suthikulpanit 
To allow specification whether to use v1 or v2 IOMMU pagetable for
DMA remapping when calling kernel DMA-API.

Signed-off-by: Suravee Suthikulpanit 
---
 Documentation/admin-guide/kernel-parameters.txt |  6 ++
 drivers/iommu/amd/init.c| 15 +++
 2 files changed, 21 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt 
b/Documentation/admin-guide/kernel-parameters.txt
index 04545725f187..466e807369ea 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -319,6 +319,12 @@
 This mode requires kvm-amd.avic=1.
 (Default when IOMMU HW support is present.)
 
+   amd_iommu_pgtable= [HW,X86-64]
+   Specifies one of the following AMD IOMMU page table to
+   be used for DMA remapping for DMA-API:
+   v1 - Use v1 page table (Default)
+   v2 - Use v2 page table
+
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: ,
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 9265c1bf1d84..6d5163bfb87e 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3123,6 +3123,20 @@ static int __init parse_amd_iommu_dump(char *str)
return 1;
 }
 
+static int __init parse_amd_iommu_pgtable(char *str)
+{
+   for (; *str; ++str) {
+   if (strncmp(str, "v1", 2) == 0) {
+   amd_iommu_pgtable = AMD_IOMMU_V1;
+   break;
+   } else if (strncmp(str, "v2", 2) == 0) {
+   amd_iommu_pgtable = AMD_IOMMU_V2;
+   break;
+   }
+   }
+   return 1;
+}
+
 static int __init parse_amd_iommu_intr(char *str)
 {
for (; *str; ++str) {
@@ -3246,6 +3260,7 @@ static int __init parse_ivrs_acpihid(char *str)
 
 __setup("amd_iommu_dump",  parse_amd_iommu_dump);
 __setup("amd_iommu=",  parse_amd_iommu_options);
+__setup("amd_iommu_pgtable=",  parse_amd_iommu_pgtable);
 __setup("amd_iommu_intr=", parse_amd_iommu_intr);
 __setup("ivrs_ioapic", parse_ivrs_ioapic);
 __setup("ivrs_hpet",   parse_ivrs_hpet);
-- 
2.17.1