LinuxLists.cc - [PATCH v8 10/17] KVM: s390: pv: add mmu

2022-03-02 22:04:36

Subject: [PATCH v8 10/17] KVM: s390: pv: add mmu_notifier

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 <[email protected]>
---
arch/s390/include/asm/kvm_host.h | 2 ++
arch/s390/kvm/kvm-s390.c | 5 ++++-
arch/s390/kvm/pv.c | 26 ++++++++++++++++++++++++++
3 files changed, 32 insertions(+), 1 deletion(-)

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/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 21fcca09e9bf..446f89db93a1 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -32,6 +32,7 @@
#include <linux/sched/signal.h>
#include <linux/string.h>
#include <linux/pgtable.h>
+#include <linux/mmu_notifier.h>

#include <asm/asm-offsets.h>
#include <asm/lowcore.h>
@@ -2833,8 +2834,10 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
* can mess with the pv state. To avoid lockdep_assert_held from
* complaining we do not use kvm_s390_pv_is_protected.
*/
- if (kvm_s390_pv_get_handle(kvm))
+ if (kvm_s390_pv_get_handle(kvm)) {
kvm_s390_pv_deinit_vm(kvm, &rc, &rrc);
+ mmu_notifier_unregister(&kvm->arch.pv.mmu_notifier, kvm->mm);
+ }
debug_unregister(kvm->arch.dbf);
free_page((unsigned long)kvm->arch.sie_page2);
if (!kvm_is_ucontrol(kvm))
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 76ef33a277d3..788b96b36931 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -14,6 +14,7 @@
#include <asm/mman.h>
#include <linux/pagewalk.h>
#include <linux/sched/mm.h>
+#include <linux/mmu_notifier.h>
#include "kvm-s390.h"

static void kvm_s390_clear_pv_state(struct kvm *kvm)
@@ -192,6 +193,26 @@ 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;
+
+ /*
+ * No locking is needed since this is the last thread of the last user of this
+ * struct mm.
+ * When the struct kvm gets deinitialized, this notifier is also
+ * unregistered. This means that if this notifier runs, then the
+ * struct kvm is still valid.
+ */
+ kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);
+}
+
+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 = {
@@ -233,6 +254,11 @@ 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;
}

--
2.34.1

2022-03-03 03:15:43

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v8 10/17] KVM: s390: pv: add mmu_notifier

2022-03-03 03:16:12

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v8 10/17] KVM: s390: pv: add mmu_notifier

Hi Claudio,

I love your patch! Yet something to improve:

[auto build test ERROR on kvm/master]
[also build test ERROR on v5.17-rc6 next-20220302]
[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/20220303-021407
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git master
config: s390-randconfig-r001-20220302 (https://download.01.org/0day-ci/archive/20220303/[email protected]/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
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/bbf278ea47b7bdfb3c72e24faffedbb8a3a5b9f9
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/20220303-021407
git checkout bbf278ea47b7bdfb3c72e24faffedbb8a3a5b9f9
# 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 <[email protected]>

All errors (new ones prefixed by >>):

In file included from arch/s390/kvm/kvm-s390.c:23:
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/kvm-s390.c:23:
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/kvm-s390.c:23:
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/kvm-s390.c:2839:3: error: implicit declaration of function 'mmu_notifier_unregister' [-Werror,-Wimplicit-function-declaration]
mmu_notifier_unregister(&kvm->arch.pv.mmu_notifier, kvm->mm);
^
arch/s390/kvm/kvm-s390.c:2839:3: note: did you mean 'preempt_notifier_unregister'?
include/linux/preempt.h:346:6: note: 'preempt_notifier_unregister' declared here
void preempt_notifier_unregister(struct preempt_notifier *notifier);
^
12 warnings and 1 error generated.
--
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:260:3: 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:260:3: 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_unregister +2839 arch/s390/kvm/kvm-s390.c

2823
2824 void kvm_arch_destroy_vm(struct kvm *kvm)
2825 {
2826 u16 rc, rrc;
2827
2828 kvm_destroy_vcpus(kvm);
2829 sca_dispose(kvm);
2830 kvm_s390_gisa_destroy(kvm);
2831 /*
2832 * We are already at the end of life and kvm->lock is not taken.
2833 * This is ok as the file descriptor is closed by now and nobody
2834 * can mess with the pv state. To avoid lockdep_assert_held from
2835 * complaining we do not use kvm_s390_pv_is_protected.
2836 */
2837 if (kvm_s390_pv_get_handle(kvm)) {
2838 kvm_s390_pv_deinit_vm(kvm, &rc, &rrc);
> 2839 mmu_notifier_unregister(&kvm->arch.pv.mmu_notifier, kvm->mm);
2840 }
2841 debug_unregister(kvm->arch.dbf);
2842 free_page((unsigned long)kvm->arch.sie_page2);
2843 if (!kvm_is_ucontrol(kvm))
2844 gmap_remove(kvm->arch.gmap);
2845 kvm_s390_destroy_adapters(kvm);
2846 kvm_s390_clear_float_irqs(kvm);
2847 kvm_s390_vsie_destroy(kvm);
2848 KVM_EVENT(3, "vm 0x%pK destroyed", kvm);
2849 }
2850

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]