linux-kernel - [tip: x86/urgent] x86/xen: Fix secondary processors' FPU initialization

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Date:   Wed, 05 Jul 2023 10:40:20 -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>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/xen: Fix secondary processors' FPU initialization

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

Commit-ID:     fe3e0a13e597c1c8617814bf9b42ab732db5c26e
Gitweb:        https://git.kernel.org/tip/fe3e0a13e597c1c8617814bf9b42ab732db5c26e
Author:        Juergen Gross <jgross@...e.com>
AuthorDate:    Mon, 03 Jul 2023 15:00:32 +02:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Wed, 05 Jul 2023 11:44:16 +02:00

x86/xen: Fix secondary processors' FPU initialization

Moving the call of fpu__init_cpu() from cpu_init() to start_secondary()
broke Xen PV guests, as those don't call start_secondary() for APs.

Call fpu__init_cpu() in Xen's cpu_bringup(), which is the Xen PV
replacement of start_secondary().

Fixes: b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()")
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>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20230703130032.22916-1-jgross@suse.com
---
 arch/x86/xen/smp_pv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index a9cf8c8..0b6efc4 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -63,6 +63,7 @@ static void cpu_bringup(void)
 
 	cr4_init();
 	cpu_init();
+	fpu__init_cpu();
 	touch_softlockup_watchdog();
 
 	/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */