On 07/24/2018 08:45 AM, M. Vefa Bicakci wrote:
> 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 <[email protected]>
> Cc: "Kirill A. Shutemov" <[email protected]>
> Cc: Andy Lutomirski <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: "H. Peter Anvin" <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Boris Ostrovsky <[email protected]>
> Cc: Juergen Gross <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected] # for v4.17 and up
> Fixes: d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment
> corruption")
Reviewed-by: Boris Ostrovsky <[email protected]>
_______________________________________________
Xen-devel mailing list
[email protected]
https://lists.xenproject.org/mailman/listinfo/xen-devel
