3.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Borislav Petkov <bp@xxxxxxx> commit 4750a0d112cbfcc744929f1530ffe3193436766c upstream. Konrad triggered the following splat below in a 32-bit guest on an AMD box. As it turns out, in save_microcode_in_initrd_amd() we're using the *physical* address of the container *after* we have enabled paging and thus we #PF in load_microcode_amd() when trying to access the microcode container in the ramdisk range. Because the ramdisk is exactly there: [ 0.000000] RAMDISK: [mem 0x35e04000-0x36ef9fff] and we fault at 0x35e04304. And since this guest doesn't relocate the ramdisk, we don't do the computation which will give us the correct virtual address and we end up with the PA. So, we should actually be using virtual addresses on 32-bit too by the time we're freeing the initrd. Do that then! Unpacking initramfs... BUG: unable to handle kernel paging request at 35d4e304 IP: [<c042e905>] load_microcode_amd+0x25/0x4a0 *pde = 00000000 Oops: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.17.1-302.fc21.i686 #1 Hardware name: Xen HVM domU, BIOS 4.4.1 10/01/2014 task: f5098000 ti: f50d0000 task.ti: f50d0000 EIP: 0060:[<c042e905>] EFLAGS: 00010246 CPU: 0 EIP is at load_microcode_amd+0x25/0x4a0 EAX: 00000000 EBX: f6e9ec4c ECX: 00001ec4 EDX: 00000000 ESI: f5d4e000 EDI: 35d4e2fc EBP: f50d1ed0 ESP: f50d1e94 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 8005003b CR2: 35d4e304 CR3: 00e33000 CR4: 000406d0 Stack: 00000000 00000000 f50d1ebc f50d1ec4 f5d4e000 c0d7735a f50d1ed0 15a3d17f f50d1ec4 00600f20 00001ec4 bfb83203 f6e9ec4c f5d4e000 c0d7735a f50d1ed8 c0d80861 f50d1ee0 c0d80429 f50d1ef0 c0d889a9 f5d4e000 c0000000 f50d1f04 Call Trace: ? unpack_to_rootfs ? unpack_to_rootfs save_microcode_in_initrd_amd save_microcode_in_initrd free_initrd_mem populate_rootfs ? unpack_to_rootfs do_one_initcall ? unpack_to_rootfs ? repair_env_string ? proc_mkdir kernel_init_freeable kernel_init ret_from_kernel_thread ? rest_init Reported-and-tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> References: https://bugzilla.redhat.com/show_bug.cgi?id=1158204 Fixes: 75a1ba5b2c52 ("x86, microcode, AMD: Unify valid container checks") Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: http://lkml.kernel.org/r/20141101100100.GA4462@xxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/cpu/microcode/amd_early.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/microcode/amd_early.c +++ b/arch/x86/kernel/cpu/microcode/amd_early.c @@ -348,6 +348,7 @@ int __init save_microcode_in_initrd_amd( { unsigned long cont; enum ucode_state ret; + u8 *cont_va; u32 eax; if (!container) @@ -355,13 +356,15 @@ int __init save_microcode_in_initrd_amd( #ifdef CONFIG_X86_32 get_bsp_sig(); - cont = (unsigned long)container; + cont = (unsigned long)container; + cont_va = __va(container); #else /* * We need the physical address of the container for both bitness since * boot_params.hdr.ramdisk_image is a physical address. */ - cont = __pa(container); + cont = __pa(container); + cont_va = container; #endif /* @@ -372,6 +375,8 @@ int __init save_microcode_in_initrd_amd( if (relocated_ramdisk) container = (u8 *)(__va(relocated_ramdisk) + (cont - boot_params.hdr.ramdisk_image)); + else + container = cont_va; if (ucode_new_rev) pr_info("microcode: updated early to new patch_level=0x%08x\n", -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html