Commit 0ae4fd90 authored by M. Vefa Bicakci's avatar M. Vefa Bicakci Committed by Greg Kroah-Hartman
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xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits

commit 405c018a upstream.

Commit d94a155c

 ("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: default avatarM. Vefa Bicakci <m.v.b@runbox.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBoris 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: d94a155c

 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 48052116
......@@ -905,7 +905,7 @@ 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;
......
......@@ -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,
......
......@@ -1259,6 +1259,9 @@ 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;
......
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