xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits

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
get_cpu_address_sizes.

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:

  enlighten_pv.c::xen_start_kernel
    mmu_pv.c::xen_reserve_special_pages
      page.h::__pa
        physaddr.c::__phys_addr
          physaddr.h::phys_addr_valid

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@runbox.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: xen-devel@lists.xenproject.org
Cc: x86@kernel.org
Cc: stable@vger.kernel.org # for v4.17 and up
Fixes: d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 6c54d8b0e5dc9000f2b483c6bdddabf60386908d..ae4f5afb9095dad083395ee5119cf59e781666e5 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -883,7 +883,7 @@ 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 cca588407dca80915a1eec1197a84e0d1f13e8f4..d0a17a438dd0044e3e84cc5e0849403bb09e77f5 100644 (file)
--- 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 int detect_extended_topology_early(struct cpuinfo_x86 *c);
 extern int detect_ht_early(struct cpuinfo_x86 *c);

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index ce8f6a8d4ac96ac2347581bd5282f3d37d4b4245..ca0fce74814b7bb6401817ff1bf27f860fc7f8d4 100644 (file)
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1258,6 +1258,9 @@ asmlinkage __visible void __init xen_start_kernel(void)
        get_cpu_cap(&boot_cpu_data);
        x86_configure_nx();
 
+       /* 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;