linux-kernel - Re: [PATCH v5 00/13] arch/x86: AMD QoS support

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Date:   Wed, 31 Oct 2018 14:55:18 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "Moger, Babu" <Babu.Moger@....com>
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Subject: Re: [PATCH v5 00/13] arch/x86: AMD QoS support

On Thu, Oct 18, 2018 at 10:52:00PM +0000, Moger, Babu wrote:
> Changes from v4 -> v5:
>  b. The functions update_mba_bw and set_mba_sc is not required for AMD.
>     Removed all the changes related to these functions.

Hi, Babu,

In v4, you says AMD won't support MBA software controller.

In v5, does AMD support MBA software controller or not? The v5 patches
show the feature is supported now. If that's a code bug, you may need
the following patch?

x86/resctrl: Only Intel RDT supports MBA software controller
    
AMD doesn't support the feature.
    
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>

diff --git a/arch/x86/kernel/cpu/resctrl_rdtgroup.c b/arch/x86/kernel/cpu/resctrl_rdtgroup.c
index 8b6b4a8bb7ca..89dd9b7c9dd7 100644
--- a/arch/x86/kernel/cpu/resctrl_rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl_rdtgroup.c
@@ -1878,9 +1878,11 @@ static int parse_rdtgroupfs_options(char *data)
 			if (ret)
 				goto out;
 		} else if (!strcmp(token, "mba_MBps")) {
-			ret = set_mba_sc(true);
-			if (ret)
-				goto out;
+			if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
+				ret = set_mba_sc(true);
+				if (ret)
+					goto out;
+			}
 		} else {
 			ret = -EINVAL;
 			goto out;