linux-kernel - [PATCH 2/2] xen/pv: Call get_cpu_address_sizes to set x86_virt/phys

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Date:   Sat, 21 Jul 2018 15:49:09 -0400
From:   "M. Vefa Bicakci" <m.v.b@...box.com>
To:     linux-kernel@...r.kernel.org
Cc:     "M . Vefa Bicakci" <m.v.b@...box.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        stable@...r.kernel.org
Subject: [PATCH 2/2] xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits

Commit d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits
adjustment corruption") has moved the query and calculation of the
"x86_virt_bits" and "x86_phys_bits" fields of the "cpuinfo_x86" struct
from the "get_cpu_cap" function to a new function named
"get_cpu_address_sizes".

One of the call sites related to Xen PV VMs was unfortunately missed
in the aforementioned commit, and this prevents successful boot-up of
kernel versions 4.17 and up in Xen PV VMs.

Signed-off-by: M. Vefa Bicakci <m.v.b@...box.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: xen-devel@...ts.xenproject.org
Cc: x86@...nel.org
Cc: stable@...r.kernel.org # for v4.17 and up
Fixes: d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
---
 arch/x86/kernel/cpu/common.c | 2 +-
 arch/x86/kernel/cpu/cpu.h    | 1 +
 arch/x86/xen/enlighten_pv.c  | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index eb4cb3efd20e..2322d0c4bfd2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -911,7 +911,7 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 	apply_forced_caps(c);
 }
 
-static void get_cpu_address_sizes(struct cpuinfo_x86 *c)
+void get_cpu_address_sizes(struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
 
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 38216f678fc3..12a5f0cec0b2 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -46,6 +46,7 @@ extern const struct cpu_dev *const __x86_cpu_dev_start[],
 			    *const __x86_cpu_dev_end[];
 
 extern void get_cpu_cap(struct cpuinfo_x86 *c);
+extern void get_cpu_address_sizes(struct cpuinfo_x86 *c);
 extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
 extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
 extern u32 get_scattered_cpuid_leaf(unsigned int level,
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 439a94bf89ad..87afb000142a 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1257,6 +1257,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 
 	/* Work out if we support NX */
 	get_cpu_cap(&boot_cpu_data);
+	get_cpu_address_sizes(&boot_cpu_data);
 	x86_configure_nx();
 
 	/* Let's presume PV guests always boot on vCPU with id 0. */
-- 
2.17.1