github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-07 22:14:04 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged

Browse Source 
commit d7eb79c629 upstream.

# lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                88
On-line CPU(s) list:   0-63
Off-line CPU(s) list:  64-87

# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-5.10.0-rc3-tlinux2-0050+ root=/dev/mapper/cl-root ro
rd.lvm.lv=cl/root rhgb quiet console=ttyS0 LANG=en_US .UTF-8 no-kvmclock-vsyscall

# echo 1 > /sys/devices/system/cpu/cpu76/online
-bash: echo: write error: Cannot allocate memory

The per-cpu vsyscall pvclock data pointer assigns either an element of the
static array hv_clock_boot (#vCPU <= 64) or dynamically allocated memory
hvclock_mem (vCPU > 64), the dynamically memory will not be allocated if
kvmclock vsyscall is disabled, this can result in cpu hotpluged fails in
kvmclock_setup_percpu() which returns -ENOMEM. It's broken for no-vsyscall
and sometimes you end up with vsyscall disabled if the host does something
strange. This patch fixes it by allocating this dynamically memory
unconditionally even if vsyscall is disabled.

Fixes: 6a1cac56f4 ("x86/kvm: Use __bss_decrypted attribute in shared variables")
Reported-by: Zelin Deng <zelin.deng@linux.alibaba.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: stable@vger.kernel.org#v4.19-rc5+
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1614130683-24137-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Wanpeng Li 2021-02-24 09:37:29 +08:00 committed by Greg Kroah-Hartman
parent 4ab5d1b709
commit a688bf8cf5
1 changed files with 12 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
arch/x86/kernel/kvmclock.c
View File

@ -269,21 +269,20 @@ static void __init kvmclock_init_mem(void)
static int __init kvm_setup_vsyscall_timeinfo(void)
{
#ifdef CONFIG_X86_64
u8 flags;
if (!per_cpu(hv_clock_per_cpu, 0) || !kvmclock_vsyscall)
return 0;
flags = pvclock_read_flags(&hv_clock_boot[0].pvti);
if (!(flags & PVCLOCK_TSC_STABLE_BIT))
return 0;
kvm_clock.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
#endif
kvmclock_init_mem();
#ifdef CONFIG_X86_64
if (per_cpu(hv_clock_per_cpu, 0) && kvmclock_vsyscall) {
u8 flags;
flags = pvclock_read_flags(&hv_clock_boot[0].pvti);
if (!(flags & PVCLOCK_TSC_STABLE_BIT))
return 0;
kvm_clock.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
}
#endif
return 0;
}
early_initcall(kvm_setup_vsyscall_timeinfo);