linux-kernel - Re: [PATCH v2] powerpc: iommu: Bring back table group release

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Message-ID: <20240201185231.GP50608@ziepe.ca>
Date: Thu, 1 Feb 2024 14:52:31 -0400
From: Jason Gunthorpe <jgg@...pe.ca>
To: Shivaprasad G Bhat <sbhat@...ux.ibm.com>
Cc: iommu@...ts.linux.dev, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org, mpe@...erman.id.au, npiggin@...il.com,
	christophe.leroy@...roup.eu, aneesh.kumar@...nel.org,
	naveen.n.rao@...ux.ibm.com, jroedel@...e.de,
	tpearson@...torengineering.com, aik@....com, bgray@...ux.ibm.com,
	gregkh@...uxfoundation.org, gbatra@...ux.vnet.ibm.com,
	vaibhav@...ux.ibm.com
Subject: Re: [PATCH v2] powerpc: iommu: Bring back table group
 release_ownership() call

On Fri, Jan 26, 2024 at 09:09:18AM -0600, Shivaprasad G Bhat wrote:
> The commit 2ad56efa80db ("powerpc/iommu: Setup a default domain and
> remove set_platform_dma_ops") refactored the code removing the
> set_platform_dma_ops(). It missed out the table group
> release_ownership() call which would have got called otherwise
> during the guest shutdown via vfio_group_detach_container(). On
> PPC64, this particular call actually sets up the 32-bit TCE table,
> and enables the 64-bit DMA bypass etc. Now after guest shutdown,
> the subsequent host driver (e.g megaraid-sas) probe post unbind
> from vfio-pci fails like,
> 
> megaraid_sas 0031:01:00.0: Warning: IOMMU dma not supported: mask 0x7fffffffffffffff, table unavailable
> megaraid_sas 0031:01:00.0: Warning: IOMMU dma not supported: mask 0xffffffff, table unavailable
> megaraid_sas 0031:01:00.0: Failed to set DMA mask
> megaraid_sas 0031:01:00.0: Failed from megasas_init_fw 6539
> 
> The patch brings back the call to table_group release_ownership()
> call when switching back to PLATFORM domain from BLOCKED, while
> also separates the domain_ops for both.
> 
> Fixes: 2ad56efa80db ("powerpc/iommu: Setup a default domain and remove set_platform_dma_ops")
> Signed-off-by: Shivaprasad G Bhat <sbhat@...ux.ibm.com>
> ---
> Changelog:
> v1: https://lore.kernel.org/linux-iommu/170618451433.3805.9015493852395837391.stgit@ltcd48-lp2.aus.stglab.ibm.com/
>  - Split the common attach_dev call to platform and blocked attach_dev
>    calls as suggested.
> 
>  arch/powerpc/kernel/iommu.c |   37 ++++++++++++++++++++++++++++---------
>  1 file changed, 28 insertions(+), 9 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

> @@ -1312,13 +1312,32 @@ static struct iommu_domain spapr_tce_platform_domain = {
>  	.ops = &spapr_tce_platform_domain_ops,
>  };
> 
> -static struct iommu_domain spapr_tce_blocked_domain = {
> -	.type = IOMMU_DOMAIN_BLOCKED,
> +static int
> +spapr_tce_blocked_iommu_attach_dev(struct iommu_domain *platform_domain,

It was my typo but this should be "struct iommu_domain *blocked_domain"

Jason