linux-kernel - Re: [PATCH] x86/amd_nb: Check for invalid SMN reads

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Message-ID: <20230403203623.GDZCs4x5yVReaPVOaS@fat_crate.local>
Date:   Mon, 3 Apr 2023 22:36:23 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <yazen.ghannam@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/amd_nb: Check for invalid SMN reads

On Mon, Apr 03, 2023 at 03:40:38PM -0400, Yazen Ghannam wrote:
> I don't think pci_write_config*() sets the PCI Error response like
> pci_read_config(), AFAICT.

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 4266b64631a4..c4caade434a7 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -181,6 +181,13 @@ static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
 		pr_warn("Error %s SMN address 0x%x.\n",
 			(write ? "writing to" : "reading from"), address);
 
+	if (!write) {
+		if (PCI_POSSIBLE_ERROR(*value)) {
+			err = -ENODEV;
+			*value = 0;
+		}
+	}
+
 out_unlock:
 	mutex_unlock(&smn_mutex);
 

-- 
Regards/Gruss,
    Boris.

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