diff mbox series

[v3] KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged

Message ID 1612168596-3782-1-git-send-email-wanpengli@tencent.com (mailing list archive)
State New, archived
Headers show
Series [v3] KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged | expand

Commit Message

Wanpeng Li Feb. 1, 2021, 8:36 a.m. UTC 
From: Wanpeng Li <wanpengli@tencent.com>

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>
Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: stable@vger.kernel.org#v4.19-rc5+
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v2 -> v3:
 * allocate dynamically memory unconditionally
v1 -> v2:
 * add code comments

 arch/x86/kernel/kvmclock.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

kernel test robot Feb. 1, 2021, 11:21 a.m. UTC | #1 
Hi Wanpeng,

I love your patch! Perhaps something to improve:

[auto build test WARNING on kvm/linux-next]
[also build test WARNING on linux/master vhost/linux-next next-20210125]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Wanpeng-Li/KVM-kvmclock-Fix-vCPUs-64-can-t-be-online-hotpluged/20210201-163927
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: x86_64-allyesconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/132ae1cea476666dff619b5a7c5675011edd7fe7
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Wanpeng-Li/KVM-kvmclock-Fix-vCPUs-64-can-t-be-online-hotpluged/20210201-163927
        git checkout 132ae1cea476666dff619b5a7c5675011edd7fe7
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   arch/x86/kernel/kvmclock.c: In function 'kvm_setup_vsyscall_timeinfo':
>> arch/x86/kernel/kvmclock.c:274:2: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
     274 |  u8 flags;
         |  ^~


vim +274 arch/x86/kernel/kvmclock.c

6a1cac56f41f9e Brijesh Singh   2018-09-14  268  
e499a9b6dc488a Thomas Gleixner 2018-07-19  269  static int __init kvm_setup_vsyscall_timeinfo(void)
e499a9b6dc488a Thomas Gleixner 2018-07-19  270  {
132ae1cea47666 Wanpeng Li      2021-02-01  271  	kvmclock_init_mem();
132ae1cea47666 Wanpeng Li      2021-02-01  272  
e499a9b6dc488a Thomas Gleixner 2018-07-19  273  #ifdef CONFIG_X86_64
e499a9b6dc488a Thomas Gleixner 2018-07-19 @274  	u8 flags;
e499a9b6dc488a Thomas Gleixner 2018-07-19  275  
95a3d4454bb1cf Thomas Gleixner 2018-07-19  276  	if (!per_cpu(hv_clock_per_cpu, 0) || !kvmclock_vsyscall)
e499a9b6dc488a Thomas Gleixner 2018-07-19  277  		return 0;
e499a9b6dc488a Thomas Gleixner 2018-07-19  278  
95a3d4454bb1cf Thomas Gleixner 2018-07-19  279  	flags = pvclock_read_flags(&hv_clock_boot[0].pvti);
e499a9b6dc488a Thomas Gleixner 2018-07-19  280  	if (!(flags & PVCLOCK_TSC_STABLE_BIT))
95a3d4454bb1cf Thomas Gleixner 2018-07-19  281  		return 0;
e499a9b6dc488a Thomas Gleixner 2018-07-19  282  
b95a8a27c300d1 Thomas Gleixner 2020-02-07  283  	kvm_clock.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
e499a9b6dc488a Thomas Gleixner 2018-07-19  284  #endif
6a1cac56f41f9e Brijesh Singh   2018-09-14  285  
e499a9b6dc488a Thomas Gleixner 2018-07-19  286  	return 0;
e499a9b6dc488a Thomas Gleixner 2018-07-19  287  }
e499a9b6dc488a Thomas Gleixner 2018-07-19  288  early_initcall(kvm_setup_vsyscall_timeinfo);
e499a9b6dc488a Thomas Gleixner 2018-07-19  289  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Feb. 1, 2021, 5:31 p.m. UTC | #2 
Hi Wanpeng,

I love your patch! Perhaps something to improve:

[auto build test WARNING on kvm/linux-next]
[also build test WARNING on linux/master vhost/linux-next next-20210125]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Wanpeng-Li/KVM-kvmclock-Fix-vCPUs-64-can-t-be-online-hotpluged/20210201-163927
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: x86_64-randconfig-a013-20210201 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 275c6af7d7f1ed63a03d05b4484413e447133269)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/132ae1cea476666dff619b5a7c5675011edd7fe7
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Wanpeng-Li/KVM-kvmclock-Fix-vCPUs-64-can-t-be-online-hotpluged/20210201-163927
        git checkout 132ae1cea476666dff619b5a7c5675011edd7fe7
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> arch/x86/kernel/kvmclock.c:274:5: warning: ISO C90 forbids mixing declarations and code [-Wdeclaration-after-statement]
           u8 flags;
              ^
   1 warning generated.


vim +274 arch/x86/kernel/kvmclock.c

6a1cac56f41f9e Brijesh Singh   2018-09-14  268  
e499a9b6dc488a Thomas Gleixner 2018-07-19  269  static int __init kvm_setup_vsyscall_timeinfo(void)
e499a9b6dc488a Thomas Gleixner 2018-07-19  270  {
132ae1cea47666 Wanpeng Li      2021-02-01  271  	kvmclock_init_mem();
132ae1cea47666 Wanpeng Li      2021-02-01  272  
e499a9b6dc488a Thomas Gleixner 2018-07-19  273  #ifdef CONFIG_X86_64
e499a9b6dc488a Thomas Gleixner 2018-07-19 @274  	u8 flags;
e499a9b6dc488a Thomas Gleixner 2018-07-19  275  
95a3d4454bb1cf Thomas Gleixner 2018-07-19  276  	if (!per_cpu(hv_clock_per_cpu, 0) || !kvmclock_vsyscall)
e499a9b6dc488a Thomas Gleixner 2018-07-19  277  		return 0;
e499a9b6dc488a Thomas Gleixner 2018-07-19  278  
95a3d4454bb1cf Thomas Gleixner 2018-07-19  279  	flags = pvclock_read_flags(&hv_clock_boot[0].pvti);
e499a9b6dc488a Thomas Gleixner 2018-07-19  280  	if (!(flags & PVCLOCK_TSC_STABLE_BIT))
95a3d4454bb1cf Thomas Gleixner 2018-07-19  281  		return 0;
e499a9b6dc488a Thomas Gleixner 2018-07-19  282  
b95a8a27c300d1 Thomas Gleixner 2020-02-07  283  	kvm_clock.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
e499a9b6dc488a Thomas Gleixner 2018-07-19  284  #endif
6a1cac56f41f9e Brijesh Singh   2018-09-14  285  
e499a9b6dc488a Thomas Gleixner 2018-07-19  286  	return 0;
e499a9b6dc488a Thomas Gleixner 2018-07-19  287  }
e499a9b6dc488a Thomas Gleixner 2018-07-19  288  early_initcall(kvm_setup_vsyscall_timeinfo);
e499a9b6dc488a Thomas Gleixner 2018-07-19  289  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index aa59374..a72b16e 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -268,6 +268,8 @@  static void __init kvmclock_init_mem(void)
 
 static int __init kvm_setup_vsyscall_timeinfo(void)
 {
+	kvmclock_init_mem();
+
 #ifdef CONFIG_X86_64
 	u8 flags;
 
@@ -281,8 +283,6 @@  static int __init kvm_setup_vsyscall_timeinfo(void)
 	kvm_clock.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
 #endif
 
-	kvmclock_init_mem();
-
 	return 0;
 }
 early_initcall(kvm_setup_vsyscall_timeinfo);