From: Juergen Gross <jgross@xxxxxxxx>
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@xxxxxxxxxxxxxxx>
Fixes: 8d152e7a5c7537 ("x86/rtc: Replace paravirt rtc check with platform legacy quirk")
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210903084937.19392-3-jgross@xxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -1187,6 +1187,11 @@ 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)
{
@@ -1354,6 +1359,8 @@ asmlinkage __visible void __init xen_sta
add_preferred_console("xenboot", 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 +
