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.

Fix that by adding the call of fpu__init_cpu() to 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@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 d5ae5de2daa2..cef78b8c89f4 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();
 	cpuhp_ap_sync_alive();
 	cpu_init();
+	fpu__init_cpu();
 	touch_softlockup_watchdog();
 
 	/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
-- 
2.35.3

On 7/3/23 9:00 AM, Juergen Gross wrote:
> 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.
> 
> Fix that by adding the call of fpu__init_cpu() to 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@suse.com>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

On 03.07.23 19:51, Boris Ostrovsky wrote:
> 
> 
> On 7/3/23 9:00 AM, Juergen Gross wrote:
>> 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.
>>
>> Fix that by adding the call of fpu__init_cpu() to 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@suse.com>
> 
> 
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> 

x86 maintainers, could this please go through the tip tree? The patch is
depending on other 6.5 patches which went in via tip.


Juergen

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@suse.com>
AuthorDate:    Mon, 03 Jul 2023 15:00:32 +02:00
Committer:     Borislav Petkov (AMD) <bp@alien8.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@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Thomas Gleixner <tglx@linutronix.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! */