From: Juergen Gross jgross@suse.com
commit f68aa100d815b5b4467fd1c3abbe3b99d65fd028 upstream.
A Xen PV guest doesn't have a legacy RTC device, so reset the legacy RTC flag. Otherwise the following WARN splat will occur at boot:
[ 1.333404] WARNING: CPU: 1 PID: 1 at /home/gross/linux/head/drivers/rtc/rtc-mc146818-lib.c:25 mc146818_get_time+0x1be/0x210 [ 1.333404] Modules linked in: [ 1.333404] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 5.14.0-rc7-default+ #282 [ 1.333404] RIP: e030:mc146818_get_time+0x1be/0x210 [ 1.333404] Code: c0 64 01 c5 83 fd 45 89 6b 14 7f 06 83 c5 64 89 6b 14 41 83 ec 01 b8 02 00 00 00 44 89 63 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 <0f> 0b 48 c7 c7 30 0e ef 82 4c 89 e6 e8 71 2a 24 00 48 c7 c0 ff ff [ 1.333404] RSP: e02b:ffffc90040093df8 EFLAGS: 00010002 [ 1.333404] RAX: 00000000000000ff RBX: ffffc90040093e34 RCX: 0000000000000000 [ 1.333404] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 000000000000000d [ 1.333404] RBP: ffffffff82ef0e30 R08: ffff888005013e60 R09: 0000000000000000 [ 1.333404] R10: ffffffff82373e9b R11: 0000000000033080 R12: 0000000000000200 [ 1.333404] R13: 0000000000000000 R14: 0000000000000002 R15: ffffffff82cdc6d4 [ 1.333404] FS: 0000000000000000(0000) GS:ffff88807d440000(0000) knlGS:0000000000000000 [ 1.333404] CS: 10000e030 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.333404] CR2: 0000000000000000 CR3: 000000000260a000 CR4: 0000000000050660 [ 1.333404] Call Trace: [ 1.333404] ? wakeup_sources_sysfs_init+0x30/0x30 [ 1.333404] ? rdinit_setup+0x2b/0x2b [ 1.333404] early_resume_init+0x23/0xa4 [ 1.333404] ? cn_proc_init+0x36/0x36 [ 1.333404] do_one_initcall+0x3e/0x200 [ 1.333404] kernel_init_freeable+0x232/0x28e [ 1.333404] ? rest_init+0xd0/0xd0 [ 1.333404] kernel_init+0x16/0x120 [ 1.333404] ret_from_fork+0x1f/0x30
Cc: stable@vger.kernel.org Fixes: 8d152e7a5c7537 ("x86/rtc: Replace paravirt rtc check with platform legacy quirk") Signed-off-by: Juergen Gross jgross@suse.com Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com Link: https://lore.kernel.org/r/20210903084937.19392-3-jgross@suse.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/xen/enlighten_pv.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -1214,6 +1214,11 @@ static void __init xen_dom0_set_legacy_f x86_platform.legacy.rtc = 1; }
+static void __init xen_domu_set_legacy_features(void) +{ + x86_platform.legacy.rtc = 0; +} + /* First C function to be called on Xen boot */ asmlinkage __visible void __init xen_start_kernel(void) { @@ -1375,6 +1380,8 @@ asmlinkage __visible void __init xen_sta add_preferred_console("hvc", 0, NULL); if (pci_xen) x86_init.pci.arch_init = pci_xen_init; + x86_platform.set_legacy_features = + xen_domu_set_legacy_features; } else { const struct dom0_vga_console_info *info = (void *)((char *)xen_start_info +