diff mbox series

[3/3] kvm/eventfd: Drain events from eventfd in irqfd_wakeup()

Message ID 20201027135523.646811-4-dwmw2@infradead.org (mailing list archive)
State New, archived
Headers show
Series Allow in-kernel consumers to drain events from eventfd | expand

Commit Message

David Woodhouse Oct. 27, 2020, 1:55 p.m. UTC 
From: David Woodhouse <dwmw@amazon.co.uk>

Don't allow the events to accumulate in the eventfd counter, drain them
as they are handled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 virt/kvm/eventfd.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

kernel test robot Oct. 27, 2020, 6:41 p.m. UTC | #1 
Hi David,

I love your patch! Yet something to improve:

[auto build test ERROR on vfio/next]
[also build test ERROR on vhost/linux-next linus/master kvm/linux-next v5.10-rc1 next-20201027]
[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/David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
base:   https://github.com/awilliam/linux-vfio.git next
config: x86_64-randconfig-s021-20201027 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-56-gc09e8239-dirty
        # https://github.com/0day-ci/linux/commit/dc45dd9af28fede8f8dd29b705b90f78cf87538c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
        git checkout dc45dd9af28fede8f8dd29b705b90f78cf87538c
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 

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/x86/kvm/../../../virt/kvm/eventfd.c: In function 'irqfd_wakeup':
>> arch/x86/kvm/../../../virt/kvm/eventfd.c:197:23: error: passing argument 1 of 'eventfd_ctx_do_read' from incompatible pointer type [-Werror=incompatible-pointer-types]
     197 |   eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
         |                       ^~~~~~~~~~~~~~~
         |                       |
         |                       struct eventfd_ctx **
   In file included from arch/x86/kvm/../../../virt/kvm/eventfd.c:21:
   include/linux/eventfd.h:44:46: note: expected 'struct eventfd_ctx *' but argument is of type 'struct eventfd_ctx **'
      44 | void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
         |                          ~~~~~~~~~~~~~~~~~~~~^~~
   cc1: some warnings being treated as errors

vim +/eventfd_ctx_do_read +197 arch/x86/kvm/../../../virt/kvm/eventfd.c

   180	
   181	/*
   182	 * Called with wqh->lock held and interrupts disabled
   183	 */
   184	static int
   185	irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
   186	{
   187		struct kvm_kernel_irqfd *irqfd =
   188			container_of(wait, struct kvm_kernel_irqfd, wait);
   189		__poll_t flags = key_to_poll(key);
   190		struct kvm_kernel_irq_routing_entry irq;
   191		struct kvm *kvm = irqfd->kvm;
   192		unsigned seq;
   193		int idx;
   194	
   195		if (flags & EPOLLIN) {
   196			u64 cnt;
 > 197			eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
   198	
   199			idx = srcu_read_lock(&kvm->irq_srcu);
   200			do {
   201				seq = read_seqcount_begin(&irqfd->irq_entry_sc);
   202				irq = irqfd->irq_entry;
   203			} while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
   204			/* An event has been signaled, inject an interrupt */
   205			if (kvm_arch_set_irq_inatomic(&irq, kvm,
   206						      KVM_USERSPACE_IRQ_SOURCE_ID, 1,
   207						      false) == -EWOULDBLOCK)
   208				schedule_work(&irqfd->inject);
   209			srcu_read_unlock(&kvm->irq_srcu, idx);
   210		}
   211	
   212		if (flags & EPOLLHUP) {
   213			/* The eventfd is closing, detach from KVM */
   214			unsigned long iflags;
   215	
   216			spin_lock_irqsave(&kvm->irqfds.lock, iflags);
   217	
   218			/*
   219			 * We must check if someone deactivated the irqfd before
   220			 * we could acquire the irqfds.lock since the item is
   221			 * deactivated from the KVM side before it is unhooked from
   222			 * the wait-queue.  If it is already deactivated, we can
   223			 * simply return knowing the other side will cleanup for us.
   224			 * We cannot race against the irqfd going away since the
   225			 * other side is required to acquire wqh->lock, which we hold
   226			 */
   227			if (irqfd_is_active(irqfd))
   228				irqfd_deactivate(irqfd);
   229	
   230			spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
   231		}
   232	
   233		return 0;
   234	}
   235	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Oct. 27, 2020, 9:42 p.m. UTC | #2 
Hi David,

I love your patch! Yet something to improve:

[auto build test ERROR on vfio/next]
[also build test ERROR on vhost/linux-next linus/master kvm/linux-next v5.10-rc1 next-20201027]
[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/David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
base:   https://github.com/awilliam/linux-vfio.git next
config: s390-randconfig-r023-20201027 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project f2c25c70791de95d2466e09b5b58fc37f6ccd7a4)
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/dc45dd9af28fede8f8dd29b705b90f78cf87538c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
        git checkout dc45dd9af28fede8f8dd29b705b90f78cf87538c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 

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/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:11:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:72:
   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:34:59: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
                                                             ^
   include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32'
           ___constant_swab32(x) :                 \
                              ^
   include/uapi/linux/swab.h:21:12: note: expanded from macro '___constant_swab32'
           (((__u32)(x) & (__u32)0x00ff0000UL) >>  8) |            \
                     ^
   In file included from arch/s390/kvm/../../../virt/kvm/eventfd.c:12:
   In file included from include/linux/kvm_host.h:32:
   In file included from include/linux/kvm_para.h:5:
   In file included from include/uapi/linux/kvm_para.h:36:
   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:11:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:72:
   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:34:59: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
                                                             ^
   include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32'
           ___constant_swab32(x) :                 \
                              ^
   include/uapi/linux/swab.h:22:12: note: expanded from macro '___constant_swab32'
           (((__u32)(x) & (__u32)0xff000000UL) >> 24)))
                     ^
   In file included from arch/s390/kvm/../../../virt/kvm/eventfd.c:12:
   In file included from include/linux/kvm_host.h:32:
   In file included from include/linux/kvm_para.h:5:
   In file included from include/uapi/linux/kvm_para.h:36:
   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:11:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:72:
   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:34:59: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
                                                             ^
   include/uapi/linux/swab.h:120:12: note: expanded from macro '__swab32'
           __fswab32(x))
                     ^
   In file included from arch/s390/kvm/../../../virt/kvm/eventfd.c:12:
   In file included from include/linux/kvm_host.h:32:
   In file included from include/linux/kvm_para.h:5:
   In file included from include/uapi/linux/kvm_para.h:36:
   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:11:
   In file included from include/linux/scatterlist.h:9:
   In file included from arch/s390/include/asm/io.h:72:
   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/../../../virt/kvm/eventfd.c:197:23: error: incompatible pointer types passing 'struct eventfd_ctx **' to parameter of type 'struct eventfd_ctx *'; remove & [-Werror,-Wincompatible-pointer-types]
                   eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
                                       ^~~~~~~~~~~~~~~
   include/linux/eventfd.h:44:46: note: passing argument to parameter 'ctx' here
   void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
                                                ^
   20 warnings and 1 error generated.

vim +197 arch/s390/kvm/../../../virt/kvm/eventfd.c

   180	
   181	/*
   182	 * Called with wqh->lock held and interrupts disabled
   183	 */
   184	static int
   185	irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
   186	{
   187		struct kvm_kernel_irqfd *irqfd =
   188			container_of(wait, struct kvm_kernel_irqfd, wait);
   189		__poll_t flags = key_to_poll(key);
   190		struct kvm_kernel_irq_routing_entry irq;
   191		struct kvm *kvm = irqfd->kvm;
   192		unsigned seq;
   193		int idx;
   194	
   195		if (flags & EPOLLIN) {
   196			u64 cnt;
 > 197			eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
   198	
   199			idx = srcu_read_lock(&kvm->irq_srcu);
   200			do {
   201				seq = read_seqcount_begin(&irqfd->irq_entry_sc);
   202				irq = irqfd->irq_entry;
   203			} while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
   204			/* An event has been signaled, inject an interrupt */
   205			if (kvm_arch_set_irq_inatomic(&irq, kvm,
   206						      KVM_USERSPACE_IRQ_SOURCE_ID, 1,
   207						      false) == -EWOULDBLOCK)
   208				schedule_work(&irqfd->inject);
   209			srcu_read_unlock(&kvm->irq_srcu, idx);
   210		}
   211	
   212		if (flags & EPOLLHUP) {
   213			/* The eventfd is closing, detach from KVM */
   214			unsigned long iflags;
   215	
   216			spin_lock_irqsave(&kvm->irqfds.lock, iflags);
   217	
   218			/*
   219			 * We must check if someone deactivated the irqfd before
   220			 * we could acquire the irqfds.lock since the item is
   221			 * deactivated from the KVM side before it is unhooked from
   222			 * the wait-queue.  If it is already deactivated, we can
   223			 * simply return knowing the other side will cleanup for us.
   224			 * We cannot race against the irqfd going away since the
   225			 * other side is required to acquire wqh->lock, which we hold
   226			 */
   227			if (irqfd_is_active(irqfd))
   228				irqfd_deactivate(irqfd);
   229	
   230			spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
   231		}
   232	
   233		return 0;
   234	}
   235	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Oct. 27, 2020, 11:13 p.m. UTC | #3 
Hi David,

I love your patch! Yet something to improve:

[auto build test ERROR on vfio/next]
[also build test ERROR on vhost/linux-next linus/master kvm/linux-next v5.10-rc1 next-20201027]
[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/David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
base:   https://github.com/awilliam/linux-vfio.git next
config: x86_64-randconfig-a004-20201026 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project f2c25c70791de95d2466e09b5b58fc37f6ccd7a4)
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/dc45dd9af28fede8f8dd29b705b90f78cf87538c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
        git checkout dc45dd9af28fede8f8dd29b705b90f78cf87538c
        # 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 errors (new ones prefixed by >>):

>> arch/x86/kvm/../../../virt/kvm/eventfd.c:197:23: error: incompatible pointer types passing 'struct eventfd_ctx **' to parameter of type 'struct eventfd_ctx *'; remove & [-Werror,-Wincompatible-pointer-types]
                   eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
                                       ^~~~~~~~~~~~~~~
   include/linux/eventfd.h:44:46: note: passing argument to parameter 'ctx' here
   void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
                                                ^
   1 error generated.

vim +197 arch/x86/kvm/../../../virt/kvm/eventfd.c

   180	
   181	/*
   182	 * Called with wqh->lock held and interrupts disabled
   183	 */
   184	static int
   185	irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
   186	{
   187		struct kvm_kernel_irqfd *irqfd =
   188			container_of(wait, struct kvm_kernel_irqfd, wait);
   189		__poll_t flags = key_to_poll(key);
   190		struct kvm_kernel_irq_routing_entry irq;
   191		struct kvm *kvm = irqfd->kvm;
   192		unsigned seq;
   193		int idx;
   194	
   195		if (flags & EPOLLIN) {
   196			u64 cnt;
 > 197			eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
   198	
   199			idx = srcu_read_lock(&kvm->irq_srcu);
   200			do {
   201				seq = read_seqcount_begin(&irqfd->irq_entry_sc);
   202				irq = irqfd->irq_entry;
   203			} while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
   204			/* An event has been signaled, inject an interrupt */
   205			if (kvm_arch_set_irq_inatomic(&irq, kvm,
   206						      KVM_USERSPACE_IRQ_SOURCE_ID, 1,
   207						      false) == -EWOULDBLOCK)
   208				schedule_work(&irqfd->inject);
   209			srcu_read_unlock(&kvm->irq_srcu, idx);
   210		}
   211	
   212		if (flags & EPOLLHUP) {
   213			/* The eventfd is closing, detach from KVM */
   214			unsigned long iflags;
   215	
   216			spin_lock_irqsave(&kvm->irqfds.lock, iflags);
   217	
   218			/*
   219			 * We must check if someone deactivated the irqfd before
   220			 * we could acquire the irqfds.lock since the item is
   221			 * deactivated from the KVM side before it is unhooked from
   222			 * the wait-queue.  If it is already deactivated, we can
   223			 * simply return knowing the other side will cleanup for us.
   224			 * We cannot race against the irqfd going away since the
   225			 * other side is required to acquire wqh->lock, which we hold
   226			 */
   227			if (irqfd_is_active(irqfd))
   228				irqfd_deactivate(irqfd);
   229	
   230			spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
   231		}
   232	
   233		return 0;
   234	}
   235	

---
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/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index d6408bb497dc..98b5cfa1d69f 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -193,6 +193,9 @@  irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 	int idx;
 
 	if (flags & EPOLLIN) {
+		u64 cnt;
+		eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
+
 		idx = srcu_read_lock(&kvm->irq_srcu);
 		do {
 			seq = read_seqcount_begin(&irqfd->irq_entry_sc);