linux-kernel - RE: [PATCH 1/1] iommu/vt-d: Correctly check format of page table in debugfs

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Message-ID: <FFF73D592F13FD46B8700F0A279B802F4F9354AF@ORSMSX114.amr.corp.intel.com>
Date:   Mon, 22 Jul 2019 05:21:37 +0000
From:   "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
CC:     "Raj, Ashok" <ashok.raj@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: RE: [PATCH 1/1] iommu/vt-d: Correctly check format of page table in
 debugfs

Hi Allen,

> diff --git a/drivers/iommu/intel-iommu-debugfs.c b/drivers/iommu/intel-
> iommu-debugfs.c
> index 73a552914455..e31c3b416351 100644
> --- a/drivers/iommu/intel-iommu-debugfs.c
> +++ b/drivers/iommu/intel-iommu-debugfs.c
> @@ -235,7 +235,7 @@ static void ctx_tbl_walk(struct seq_file *m, struct
> intel_iommu *iommu, u16 bus)
>  		tbl_wlk.ctx_entry = context;
>  		m->private = &tbl_wlk;
> 
> -		if (pasid_supported(iommu) && is_pasid_enabled(context)) {
> +		if (dmar_readq(iommu->reg + DMAR_RTADDR_REG) &
> DMA_RTADDR_SMT) {

Thanks for adding this, I do believe this is a good addition but I also think that we might 
need "is_pasid_enabled()" as well. It checks if PASIDE bit in context entry is enabled or not.

I am thinking that even though DMAR might be using scalable root and context table, the entry 
itself should have PASIDE bit set. Did I miss something here?

And I also think a macro would be better so that it could reused elsewhere (if need be).

Regards,
Sai