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

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Date:   Mon, 3 Apr 2023 17:36:40 -0400
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     yazen.ghannam@....com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/amd_nb: Check for invalid SMN reads

On 4/3/23 16:36, Borislav Petkov wrote:
> 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);
>  
> 

Yes, that's fine. Should I send another revision?

Thanks,
Yazen