Re: [PATCH v1 11/26] x86/sev: Invalidate pages from the direct map when adding them to the RMP table

[Borislav Petkov]

On Sat, Dec 30, 2023 at 10:19:39AM -0600, Michael Roth wrote:
> +	/*
> +	 * If the kernel uses a 2MB directmap mapping to write to an address,
> +	 * and that 2MB range happens to contain a 4KB page that set to private
> +	 * in the RMP table, an RMP #PF will trigger and cause a host crash.

Also:

diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 7d294d1a620b..2ad83e7fb2da 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -415,8 +415,9 @@ static int rmpupdate(u64 pfn, struct rmp_state *state)
 
 	/*
 	 * If the kernel uses a 2MB directmap mapping to write to an address,
-	 * and that 2MB range happens to contain a 4KB page that set to private
-	 * in the RMP table, an RMP #PF will trigger and cause a host crash.
+	 * and that 2MB range happens to contain a 4KB page that has been set
+	 * to private in the RMP table, an RMP #PF will trigger and cause a
+	 * host crash.
 	 *
 	 * Prevent this by removing pages from the directmap prior to setting
 	 * them as private in the RMP table.

-- 
Regards/Gruss,
    Boris.

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