linux-kernel - [tip: x86/mtrr] x86/xen: Set default memory type for PV guests to WB

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Date:   Fri, 16 Jun 2023 09:33:07 -0000
From:   "tip-bot2 for Juergen Gross" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        "Borislav Petkov (AMD)" <bp@...en8.de>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/mtrr] x86/xen: Set default memory type for PV guests to WB

The following commit has been merged into the x86/mtrr branch of tip:

Commit-ID:     30d65d1b19850c9bc8c17dba8ebe9be5e0c17054
Gitweb:        https://git.kernel.org/tip/30d65d1b19850c9bc8c17dba8ebe9be5e0c17054
Author:        Juergen Gross <jgross@...e.com>
AuthorDate:    Thu, 15 Jun 2023 14:39:59 +02:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Fri, 16 Jun 2023 11:22:33 +02:00

x86/xen: Set default memory type for PV guests to WB

When running as an unprivileged PV guest under Xen (not dom0), the
default MTRR memory type should be write-back.

Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Link: https://lore.kernel.org/r/20230615123959.12298-1-jgross@suse.com
---
 arch/x86/xen/enlighten_pv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 8732b85..93b6582 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -187,6 +187,8 @@ static void __init xen_pv_init_platform(void)
 
 	if (xen_initial_domain())
 		xen_set_mtrr_data();
+	else
+		mtrr_overwrite_state(NULL, 0, MTRR_TYPE_WRBACK);
 }
 
 static void __init xen_pv_guest_late_init(void)