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Message-ID: <20240206113125.GCZcIYjYFz_LGJLTU5@fat_crate.local>
Date: Tue, 6 Feb 2024 12:31:25 +0100
From: Borislav Petkov <bp@...en8.de>
To: Ashish Kalra <Ashish.Kalra@....com>
Cc: x86@...nel.org, iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
thomas.lendacky@....com, michael.roth@....com,
dan.carpenter@...aro.org
Subject: Re: [PATCH] iommu/amd: Fix failure return from snp_lookup_rmpentry().
On Mon, Feb 05, 2024 at 09:06:54PM +0000, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@....com>
>
> The patch f366a8dac1b8: "iommu/amd: Clean up RMP entries for IOMMU
> pages during SNP shutdown" (linux-next), leads to the following
Add this:
[alias]
one = show -s --pretty='format:%h (\"%s\")'
to your .git/config so that when you do
$ git one f366a8dac1b8
it can give you the proper formatting for commit references:
f366a8dac1b8 ("iommu/amd: Clean up RMP entries for IOMMU pages during SNP shutdown")
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 88bb08ae39b2..11340380111d 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -3813,9 +3813,11 @@ static int iommu_page_make_shared(void *page)
> bool assigned;
>
> ret = snp_lookup_rmpentry(pfn, &assigned, &level);
> - if (ret)
> + if (ret) {
> pr_warn("IOMMU PFN %lx RMP lookup failed, ret %d\n",
> pfn, ret);
> + return ret;
> + }
This one is incomplete and we should've caught this in review: any of
those failure cases here should return an error and not attempt to make
a pfn shared again.
Diff ontop:
---
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 11340380111d..480e7681f4f3 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3814,24 +3814,27 @@ static int iommu_page_make_shared(void *page)
ret = snp_lookup_rmpentry(pfn, &assigned, &level);
if (ret) {
- pr_warn("IOMMU PFN %lx RMP lookup failed, ret %d\n",
- pfn, ret);
+ pr_warn("IOMMU PFN %lx RMP lookup failed, ret %d\n", pfn, ret);
return ret;
}
- if (!assigned)
- pr_warn("IOMMU PFN %lx not assigned in RMP table\n",
- pfn);
+ if (!assigned) {
+ pr_warn("IOMMU PFN %lx not assigned in RMP table\n", pfn);
+ return -EINVAL;
+ }
if (level > PG_LEVEL_4K) {
ret = psmash(pfn);
- if (ret) {
- pr_warn("IOMMU PFN %lx had a huge RMP entry, but attempted psmash failed, ret: %d, level: %d\n",
- pfn, ret, level);
- }
+ if (!ret)
+ goto done;
+
+ pr_warn("PSMASH failed for IOMMU PFN %lx huge RMP entry, ret: %d, level: %d\n",
+ pfn, ret, level);
+ return ret;
}
}
+done:
return rmp_make_shared(pfn, PG_LEVEL_4K);
}
--
Regards/Gruss,
Boris.
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