diff mbox series

[v7,10/17] KVM: s390: pv: add mmu_notifier

Message ID 20220204155349.63238-11-imbrenda@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series KVM: s390: pv: implement lazy destroy for reboot | expand

Commit Message

Claudio Imbrenda Feb. 4, 2022, 3:53 p.m. UTC 
Add an mmu_notifier for protected VMs. The callback function is
triggered when the mm is torn down, and will attempt to convert all
protected vCPUs to non-protected. This allows the mm teardown to use
the destroy page UVC instead of export.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  2 ++
 arch/s390/kvm/pv.c               | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

Comments

kernel test robot Feb. 4, 2022, 9:22 p.m. UTC | #1 
Hi Claudio,

I love your patch! Yet something to improve:

[auto build test ERROR on kvm/queue]
[also build test ERROR on v5.17-rc2 next-20220204]
[cannot apply to kvms390/next s390/features]
[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/Claudio-Imbrenda/KVM-s390-pv-implement-lazy-destroy-for-reboot/20220204-235609
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: s390-randconfig-r044-20220131 (https://download.01.org/0day-ci/archive/20220205/202202050525.5A9HirW8-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project a73e4ce6a59b01f0e37037761c1e6889d539d233)
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 s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/0day-ci/linux/commit/9ee65f25ad996d38f6935360c99a89e72024174b
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Claudio-Imbrenda/KVM-s390-pv-implement-lazy-destroy-for-reboot/20220204-235609
        git checkout 9ee65f25ad996d38f6935360c99a89e72024174b
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash arch/s390/kvm/

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

All errors (new ones prefixed by >>):

   In file included from arch/s390/kvm/pv.c:9:
   In file included from include/linux/kvm_host.h:41:
   In file included from include/linux/kvm_para.h:5:
   In file included from include/uapi/linux/kvm_para.h:37:
   In file included from arch/s390/include/asm/kvm_para.h:25:
   In file included from arch/s390/include/asm/diag.h:12:
   In file included from include/linux/if_ether.h:19:
   In file included from include/linux/skbuff.h:31:
   In file included from include/linux/dma-mapping.h:10:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:75:
   include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/big_endian.h:37:59: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
                                                             ^
   include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
   #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
                                                        ^
   In file included from arch/s390/kvm/pv.c:9:
   In file included from include/linux/kvm_host.h:41:
   In file included from include/linux/kvm_para.h:5:
   In file included from include/uapi/linux/kvm_para.h:37:
   In file included from arch/s390/include/asm/kvm_para.h:25:
   In file included from arch/s390/include/asm/diag.h:12:
   In file included from include/linux/if_ether.h:19:
   In file included from include/linux/skbuff.h:31:
   In file included from include/linux/dma-mapping.h:10:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:75:
   include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/big_endian.h:35:59: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
                                                             ^
   include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
   #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
                                                        ^
   In file included from arch/s390/kvm/pv.c:9:
   In file included from include/linux/kvm_host.h:41:
   In file included from include/linux/kvm_para.h:5:
   In file included from include/uapi/linux/kvm_para.h:37:
   In file included from arch/s390/include/asm/kvm_para.h:25:
   In file included from arch/s390/include/asm/diag.h:12:
   In file included from include/linux/if_ether.h:19:
   In file included from include/linux/skbuff.h:31:
   In file included from include/linux/dma-mapping.h:10:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:75:
   include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           readsb(PCI_IOBASE + addr, buffer, count);
                  ~~~~~~~~~~ ^
   include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           readsw(PCI_IOBASE + addr, buffer, count);
                  ~~~~~~~~~~ ^
   include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           readsl(PCI_IOBASE + addr, buffer, count);
                  ~~~~~~~~~~ ^
   include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           writesb(PCI_IOBASE + addr, buffer, count);
                   ~~~~~~~~~~ ^
   include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           writesw(PCI_IOBASE + addr, buffer, count);
                   ~~~~~~~~~~ ^
   include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           writesl(PCI_IOBASE + addr, buffer, count);
                   ~~~~~~~~~~ ^
>> arch/s390/kvm/pv.c:255:3: error: implicit declaration of function 'mmu_notifier_register' [-Werror,-Wimplicit-function-declaration]
                   mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
                   ^
   arch/s390/kvm/pv.c:255:3: note: did you mean 'mmu_notifier_release'?
   include/linux/mmu_notifier.h:679:20: note: 'mmu_notifier_release' declared here
   static inline void mmu_notifier_release(struct mm_struct *mm)
                      ^
   12 warnings and 1 error generated.


vim +/mmu_notifier_register +255 arch/s390/kvm/pv.c

   210	
   211	int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
   212	{
   213		struct uv_cb_cgc uvcb = {
   214			.header.cmd = UVC_CMD_CREATE_SEC_CONF,
   215			.header.len = sizeof(uvcb)
   216		};
   217		int cc, ret;
   218		u16 dummy;
   219	
   220		ret = kvm_s390_pv_alloc_vm(kvm);
   221		if (ret)
   222			return ret;
   223	
   224		/* Inputs */
   225		uvcb.guest_stor_origin = 0; /* MSO is 0 for KVM */
   226		uvcb.guest_stor_len = kvm->arch.pv.guest_len;
   227		uvcb.guest_asce = kvm->arch.gmap->asce;
   228		uvcb.guest_sca = (unsigned long)kvm->arch.sca;
   229		uvcb.conf_base_stor_origin = (u64)kvm->arch.pv.stor_base;
   230		uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var;
   231	
   232		cc = uv_call_sched(0, (u64)&uvcb);
   233		*rc = uvcb.header.rc;
   234		*rrc = uvcb.header.rrc;
   235		KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x",
   236			     uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc);
   237	
   238		/* Outputs */
   239		kvm->arch.pv.handle = uvcb.guest_handle;
   240	
   241		atomic_inc(&kvm->mm->context.protected_count);
   242		if (cc) {
   243			if (uvcb.header.rc & UVC_RC_NEED_DESTROY) {
   244				kvm_s390_pv_deinit_vm(kvm, &dummy, &dummy);
   245			} else {
   246				atomic_dec(&kvm->mm->context.protected_count);
   247				kvm_s390_pv_dealloc_vm(kvm);
   248			}
   249			return -EIO;
   250		}
   251		kvm->arch.gmap->guest_handle = uvcb.guest_handle;
   252		/* Add the notifier only once. No races because we hold kvm->lock */
   253		if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) {
   254			kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops;
 > 255			mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
   256		}
   257		return 0;
   258	}
   259	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Feb. 4, 2022, 9:22 p.m. UTC | #2 
Hi Claudio,

I love your patch! Yet something to improve:

[auto build test ERROR on kvm/queue]
[also build test ERROR on v5.17-rc2 next-20220204]
[cannot apply to kvms390/next s390/features]
[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/Claudio-Imbrenda/KVM-s390-pv-implement-lazy-destroy-for-reboot/20220204-235609
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: s390-randconfig-r044-20220203 (https://download.01.org/0day-ci/archive/20220205/202202050519.HMLLILGz-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 11.2.0
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
        # https://github.com/0day-ci/linux/commit/9ee65f25ad996d38f6935360c99a89e72024174b
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Claudio-Imbrenda/KVM-s390-pv-implement-lazy-destroy-for-reboot/20220204-235609
        git checkout 9ee65f25ad996d38f6935360c99a89e72024174b
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=s390 SHELL=/bin/bash arch/s390/kvm/

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

All errors (new ones prefixed by >>):

   arch/s390/kvm/pv.c: In function 'kvm_s390_pv_init_vm':
>> arch/s390/kvm/pv.c:255:17: error: implicit declaration of function 'mmu_notifier_register'; did you mean 'mmu_notifier_release'? [-Werror=implicit-function-declaration]
     255 |                 mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
         |                 ^~~~~~~~~~~~~~~~~~~~~
         |                 mmu_notifier_release
   cc1: some warnings being treated as errors


vim +255 arch/s390/kvm/pv.c

   210	
   211	int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
   212	{
   213		struct uv_cb_cgc uvcb = {
   214			.header.cmd = UVC_CMD_CREATE_SEC_CONF,
   215			.header.len = sizeof(uvcb)
   216		};
   217		int cc, ret;
   218		u16 dummy;
   219	
   220		ret = kvm_s390_pv_alloc_vm(kvm);
   221		if (ret)
   222			return ret;
   223	
   224		/* Inputs */
   225		uvcb.guest_stor_origin = 0; /* MSO is 0 for KVM */
   226		uvcb.guest_stor_len = kvm->arch.pv.guest_len;
   227		uvcb.guest_asce = kvm->arch.gmap->asce;
   228		uvcb.guest_sca = (unsigned long)kvm->arch.sca;
   229		uvcb.conf_base_stor_origin = (u64)kvm->arch.pv.stor_base;
   230		uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var;
   231	
   232		cc = uv_call_sched(0, (u64)&uvcb);
   233		*rc = uvcb.header.rc;
   234		*rrc = uvcb.header.rrc;
   235		KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x",
   236			     uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc);
   237	
   238		/* Outputs */
   239		kvm->arch.pv.handle = uvcb.guest_handle;
   240	
   241		atomic_inc(&kvm->mm->context.protected_count);
   242		if (cc) {
   243			if (uvcb.header.rc & UVC_RC_NEED_DESTROY) {
   244				kvm_s390_pv_deinit_vm(kvm, &dummy, &dummy);
   245			} else {
   246				atomic_dec(&kvm->mm->context.protected_count);
   247				kvm_s390_pv_dealloc_vm(kvm);
   248			}
   249			return -EIO;
   250		}
   251		kvm->arch.gmap->guest_handle = uvcb.guest_handle;
   252		/* Add the notifier only once. No races because we hold kvm->lock */
   253		if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) {
   254			kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops;
 > 255			mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
   256		}
   257		return 0;
   258	}
   259	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Janosch Frank Feb. 7, 2022, 11:04 a.m. UTC | #3 
On 2/4/22 16:53, Claudio Imbrenda wrote:
> Add an mmu_notifier for protected VMs. The callback function is
> triggered when the mm is torn down, and will attempt to convert all
> protected vCPUs to non-protected. This allows the mm teardown to use
> the destroy page UVC instead of export.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>   arch/s390/include/asm/kvm_host.h |  2 ++
>   arch/s390/kvm/pv.c               | 20 ++++++++++++++++++++
>   2 files changed, 22 insertions(+)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index a22c9266ea05..1bccb8561ba9 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -19,6 +19,7 @@
>   #include <linux/kvm.h>
>   #include <linux/seqlock.h>
>   #include <linux/module.h>
> +#include <linux/mmu_notifier.h>
>   #include <asm/debug.h>
>   #include <asm/cpu.h>
>   #include <asm/fpu/api.h>
> @@ -921,6 +922,7 @@ struct kvm_s390_pv {
>   	u64 guest_len;
>   	unsigned long stor_base;
>   	void *stor_var;
> +	struct mmu_notifier mmu_notifier;
>   };
>   
>   struct kvm_arch{
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index f1e812a45acb..d3b8fd9b5b3e 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -193,6 +193,21 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
>   	return -EIO;
>   }
>   
> +static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
> +					     struct mm_struct *mm)
> +{
> +	struct kvm *kvm = container_of(subscription, struct kvm, arch.pv.mmu_notifier);

Are we sure that the kvm pointer is still valid at this point?

> +	u16 dummy;
> +
> +	mutex_lock(&kvm->lock);

Against what are we locking here?

> +	kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);

I'd guess that we can't really have a second kvm_s390_cpus_from_pv() 
call in flight, right? If the mm is being torn down there would be no 
code left that can execute the IOCTL.

> +	mutex_unlock(&kvm->lock);
> +}
> +
> +static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {
> +	.release = kvm_s390_pv_mmu_notifier_release,
> +};
> +
>   int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
>   {
>   	struct uv_cb_cgc uvcb = {
> @@ -234,6 +249,11 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
>   		return -EIO;
>   	}
>   	kvm->arch.gmap->guest_handle = uvcb.guest_handle;
> +	/* Add the notifier only once. No races because we hold kvm->lock */
> +	if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) {
> +		kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops;
> +		mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
> +	}
>   	return 0;
>   }
>   
>
Claudio Imbrenda Feb. 7, 2022, 12:16 p.m. UTC | #4 
On Mon, 7 Feb 2022 12:04:56 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 2/4/22 16:53, Claudio Imbrenda wrote:
> > Add an mmu_notifier for protected VMs. The callback function is
> > triggered when the mm is torn down, and will attempt to convert all
> > protected vCPUs to non-protected. This allows the mm teardown to use
> > the destroy page UVC instead of export.
> > 
> > Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> > ---
> >   arch/s390/include/asm/kvm_host.h |  2 ++
> >   arch/s390/kvm/pv.c               | 20 ++++++++++++++++++++
> >   2 files changed, 22 insertions(+)
> > 
> > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> > index a22c9266ea05..1bccb8561ba9 100644
> > --- a/arch/s390/include/asm/kvm_host.h
> > +++ b/arch/s390/include/asm/kvm_host.h
> > @@ -19,6 +19,7 @@
> >   #include <linux/kvm.h>
> >   #include <linux/seqlock.h>
> >   #include <linux/module.h>
> > +#include <linux/mmu_notifier.h>
> >   #include <asm/debug.h>
> >   #include <asm/cpu.h>
> >   #include <asm/fpu/api.h>
> > @@ -921,6 +922,7 @@ struct kvm_s390_pv {
> >   	u64 guest_len;
> >   	unsigned long stor_base;
> >   	void *stor_var;
> > +	struct mmu_notifier mmu_notifier;
> >   };
> >   
> >   struct kvm_arch{
> > diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> > index f1e812a45acb..d3b8fd9b5b3e 100644
> > --- a/arch/s390/kvm/pv.c
> > +++ b/arch/s390/kvm/pv.c
> > @@ -193,6 +193,21 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
> >   	return -EIO;
> >   }
> >   
> > +static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
> > +					     struct mm_struct *mm)
> > +{
> > +	struct kvm *kvm = container_of(subscription, struct kvm, arch.pv.mmu_notifier);  
> 
> Are we sure that the kvm pointer is still valid at this point?

it should be, because KVM is torn down after the mm. which is the whole
reason why the notifier is needed.

on the other hand, I realized that I should have unregistered the
notifier somewhere, which I forgot to do. the best place would be KVM
teardown, which then also guarantees that the notifier can only be
called with a valid struct kvm

> 
> > +	u16 dummy;
> > +
> > +	mutex_lock(&kvm->lock);  
> 
> Against what are we locking here?
> 
> > +	kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);  
> 
> I'd guess that we can't really have a second kvm_s390_cpus_from_pv() 
> call in flight, right? If the mm is being torn down there would be no 
> code left that can execute the IOCTL.

yeah makes sense

> 
> > +	mutex_unlock(&kvm->lock);
> > +}
> > +
> > +static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {
> > +	.release = kvm_s390_pv_mmu_notifier_release,
> > +};
> > +
> >   int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
> >   {
> >   	struct uv_cb_cgc uvcb = {
> > @@ -234,6 +249,11 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
> >   		return -EIO;
> >   	}
> >   	kvm->arch.gmap->guest_handle = uvcb.guest_handle;
> > +	/* Add the notifier only once. No races because we hold kvm->lock */
> > +	if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) {
> > +		kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops;
> > +		mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
> > +	}
> >   	return 0;
> >   }
> >   
> >   
>
diff mbox series

Patch

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a22c9266ea05..1bccb8561ba9 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -19,6 +19,7 @@ 
 #include <linux/kvm.h>
 #include <linux/seqlock.h>
 #include <linux/module.h>
+#include <linux/mmu_notifier.h>
 #include <asm/debug.h>
 #include <asm/cpu.h>
 #include <asm/fpu/api.h>
@@ -921,6 +922,7 @@  struct kvm_s390_pv {
 	u64 guest_len;
 	unsigned long stor_base;
 	void *stor_var;
+	struct mmu_notifier mmu_notifier;
 };
 
 struct kvm_arch{
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index f1e812a45acb..d3b8fd9b5b3e 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -193,6 +193,21 @@  int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 	return -EIO;
 }
 
+static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
+					     struct mm_struct *mm)
+{
+	struct kvm *kvm = container_of(subscription, struct kvm, arch.pv.mmu_notifier);
+	u16 dummy;
+
+	mutex_lock(&kvm->lock);
+	kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);
+	mutex_unlock(&kvm->lock);
+}
+
+static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {
+	.release = kvm_s390_pv_mmu_notifier_release,
+};
+
 int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 {
 	struct uv_cb_cgc uvcb = {
@@ -234,6 +249,11 @@  int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 		return -EIO;
 	}
 	kvm->arch.gmap->guest_handle = uvcb.guest_handle;
+	/* Add the notifier only once. No races because we hold kvm->lock */
+	if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) {
+		kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops;
+		mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
+	}
 	return 0;
 }