[PATCH 4.18 06/22] xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits

From: Greg Kroah-Hartman
Date: Thu Aug 16 2018 - 14:49:44 EST

4.18-stable review patch. If anyone has any objections, please let me know.


From: M. Vefa Bicakci <m.v.b@xxxxxxxxxx>

commit 405c018a25fe464dc68057bbc8014a58f2bd4422 upstream.

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

One of the call sites related to Xen PV VMs was unfortunately missed
in the aforementioned commit. This prevents successful boot-up of
kernel versions 4.17 and up in Xen PV VMs if CONFIG_DEBUG_VIRTUAL
is enabled, due to the following code path:


phys_addr_valid uses boot_cpu_data.x86_phys_bits to validate physical
addresses. boot_cpu_data.x86_phys_bits is no longer populated before
the call to xen_reserve_special_pages due to the aforementioned commit
though, so the validation performed by phys_addr_valid fails, which
causes __phys_addr to trigger a BUG, preventing boot-up.

Signed-off-by: M. Vefa Bicakci <m.v.b@xxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # for v4.17 and up
Fixes: d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/x86/kernel/cpu/common.c | 2 +-
arch/x86/kernel/cpu/cpu.h | 1 +
arch/x86/xen/enlighten_pv.c | 3 +++
3 files changed, 5 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -905,7 +905,7 @@ void get_cpu_cap(struct cpuinfo_x86 *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;

--- 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
*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,
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1259,6 +1259,9 @@ asmlinkage __visible void __init xen_sta

+ /* Determine virtual and physical address sizes */
+ get_cpu_address_sizes(&boot_cpu_data);
/* Let's presume PV guests always boot on vCPU with id 0. */
per_cpu(xen_vcpu_id, 0) = 0;