From ae89ba3f3a3b0b68aa29c6c09361d32526b01fc7 Mon Sep 17 00:00:00 2001 From: Boris Ostrovsky Date: Wed, 3 May 2017 16:20:51 -0400 Subject: [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized Routines that are set by xen_init_time_ops() use shared_info's pvclock_vcpu_time_info area. This area is not properly available until shared_info is mapped in xen_setup_shared_info(). This became especially problematic due to commit dd759d93f4dd ("x86/timers: Add simple udelay calibration") where we end up reading tsc_to_system_mul from xen_dummy_shared_info (i.e. getting zero value) and then trying to divide by it in pvclock_tsc_khz(). Signed-off-by: Boris Ostrovsky Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross OraBug: 26662731 (cherry picked from commit d162809f85b4f54ef075517ffa2f3d02e55d5a53) Signed-off-by: Boris Ostrovsky Reviewed-by: Joao Martins Conflicts: arch/x86/xen/enlighten_pv.c (No enlighten_pv.c in our tree. Note also that we don't have dd759d93f4dd. Still, this fixes a latent bug). --- arch/x86/xen/enlighten.c | 9 +++++++-- arch/x86/xen/time.c | 2 +- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 42c6fefbbe19..96062f109fbb 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1160,6 +1160,13 @@ void xen_setup_shared_info(void) #endif xen_setup_mfn_list_list(); + + /* + * Now that shared info is set up we can start using routines that + * point to pvclock area. + */ + if (system_state == SYSTEM_BOOTING) + xen_init_time_ops(); } /* This is called once we have the cpu_possible_mask */ @@ -1505,8 +1512,6 @@ asmlinkage __visible void __init xen_start_kernel(void) x86_init.oem.arch_setup = xen_arch_setup; x86_init.oem.banner = xen_banner; - xen_init_time_ops(); - /* * Set up some pagetable state before starting to set any ptes. */ diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index a4f0e5d89c4f..66e320c00db5 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -504,7 +504,7 @@ static void __init xen_time_init(void) pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier); } -void __init xen_init_time_ops(void) +void __ref xen_init_time_ops(void) { pv_time_ops = xen_time_ops; -- 2.50.1