linux-kernel - [PATCH v2 3/3] x86/acpi/cstate: add Zhaoxin processors support for cache flush policy in C3

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Message-ID: <a370503660994669991a7f7cda7c5e98@zhaoxin.com>
Date:   Tue, 18 Jun 2019 08:37:29 +0000
From:   Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "lenb@...nel.org" <lenb@...nel.org>
CC:     David Wang <DavidWang@...oxin.com>,
        "Cooper Yan(BJ-RD)" <CooperYan@...oxin.com>,
        "Qiyuan Wang(BJ-RD)" <QiyuanWang@...oxin.com>,
        "Herry Yang(BJ-RD)" <HerryYang@...oxin.com>
Subject: [PATCH v2 3/3] x86/acpi/cstate: add Zhaoxin processors support for
 cache flush policy in C3

Same as Intel, Zhaoxin MP CPUs support C3 share cache and on all
recent Zhaoxin platforms ARB_DISABLE is a nop. So set related
flags correctly in the same way as Intel does.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
---
 arch/x86/kernel/acpi/cstate.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index a5e5484..caf2edc 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -64,6 +64,21 @@ void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
 		    c->x86_stepping >= 0x0e))
 			flags->bm_check = 1;
 	}
+
+	if (c->x86_vendor == X86_VENDOR_ZHAOXIN) {
+		/*
+		 * All Zhaoxin CPUs that support C3 share cache.
+		 * And caches should not be flushed by software while
+		 * entering C3 type state.
+		 */
+		flags->bm_check = 1;
+		/*
+		 * On all recent Zhaoxin platforms, ARB_DISABLE is a nop.
+		 * So, set bm_control to zero to indicate that ARB_DISABLE
+		 * is not required while entering C3 type state.
+		 */
+		flags->bm_control = 0;
+	}
 }
 EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
 
-- 
2.7.4