diff options
| -rwxr-xr-x | configure | 42 | ||||
| -rw-r--r-- | include/qemu/sys_membarrier.h | 10 | ||||
| -rw-r--r-- | util/Makefile.objs | 1 | ||||
| -rw-r--r-- | util/sys_membarrier.c | 50 |
4 files changed, 102 insertions, 1 deletions
@@ -342,7 +342,7 @@ attr="" libattr="" xfs="" tcg="yes" - +membarrier="" vhost_net="no" vhost_crypto="no" vhost_scsi="no" @@ -1161,6 +1161,10 @@ for opt do ;; --enable-attr) attr="yes" ;; + --disable-membarrier) membarrier="no" + ;; + --enable-membarrier) membarrier="yes" + ;; --disable-blobs) blobs="no" ;; --with-pkgversion=*) pkgversion="$optarg" @@ -1577,6 +1581,7 @@ disabled with --disable-FEATURE, default is enabled if available: xen-pci-passthrough brlapi BrlAPI (Braile) curl curl connectivity + membarrier membarrier system call (for Linux 4.14+ or Windows) fdt fdt device tree bluez bluez stack connectivity kvm KVM acceleration support @@ -5138,6 +5143,37 @@ if compile_prog "" "" ; then fi ########################################## +# check for usable membarrier system call +if test "$membarrier" = "yes"; then + have_membarrier=no + if test "$mingw32" = "yes" ; then + have_membarrier=yes + elif test "$linux" = "yes" ; then + cat > $TMPC << EOF + #include <linux/membarrier.h> + #include <sys/syscall.h> + #include <unistd.h> + #include <stdlib.h> + int main(void) { + syscall(__NR_membarrier, MEMBARRIER_CMD_QUERY, 0); + syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, 0); + exit(0); + } +EOF + if compile_prog "" "" ; then + have_membarrier=yes + fi + fi + if test "$have_membarrier" = "no"; then + feature_not_found "membarrier" "membarrier system call not available" + fi +else + # Do not enable it by default even for Mingw32, because it doesn't + # work on Wine. + membarrier=no +fi + +########################################## # check if rtnetlink.h exists and is useful have_rtnetlink=no cat > $TMPC << EOF @@ -5763,6 +5799,7 @@ fi echo "malloc trim support $malloc_trim" echo "RDMA support $rdma" echo "fdt support $fdt" +echo "membarrier $membarrier" echo "preadv support $preadv" echo "fdatasync $fdatasync" echo "madvise $madvise" @@ -6245,6 +6282,9 @@ fi if test "$fdt" = "yes" ; then echo "CONFIG_FDT=y" >> $config_host_mak fi +if test "$membarrier" = "yes" ; then + echo "CONFIG_MEMBARRIER=y" >> $config_host_mak +fi if test "$signalfd" = "yes" ; then echo "CONFIG_SIGNALFD=y" >> $config_host_mak fi diff --git a/include/qemu/sys_membarrier.h b/include/qemu/sys_membarrier.h index 9ce7f5210b..316e3dc4a2 100644 --- a/include/qemu/sys_membarrier.h +++ b/include/qemu/sys_membarrier.h @@ -9,9 +9,19 @@ #ifndef QEMU_SYS_MEMBARRIER_H #define QEMU_SYS_MEMBARRIER_H 1 +#ifdef CONFIG_MEMBARRIER +/* Only block reordering at the compiler level in the performance-critical + * side. The slow side forces processor-level ordering on all other cores + * through a system call. + */ +extern void smp_mb_global_init(void); +extern void smp_mb_global(void); +#define smp_mb_placeholder() barrier() +#else /* Keep it simple, execute a real memory barrier on both sides. */ static inline void smp_mb_global_init(void) {} #define smp_mb_global() smp_mb() #define smp_mb_placeholder() smp_mb() +#endif #endif diff --git a/util/Makefile.objs b/util/Makefile.objs index ae90b9963d..728c3541db 100644 --- a/util/Makefile.objs +++ b/util/Makefile.objs @@ -33,6 +33,7 @@ util-obj-y += throttle.o util-obj-y += getauxval.o util-obj-y += readline.o util-obj-y += rcu.o +util-obj-$(CONFIG_MEMBARRIER) += sys_membarrier.o util-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o util-obj-y += qemu-coroutine-sleep.o util-obj-y += coroutine-$(CONFIG_COROUTINE_BACKEND).o diff --git a/util/sys_membarrier.c b/util/sys_membarrier.c new file mode 100644 index 0000000000..8dcb53e63e --- /dev/null +++ b/util/sys_membarrier.c @@ -0,0 +1,50 @@ +/* + * Process-global memory barriers + * + * Copyright (c) 2018 Red Hat, Inc. + * + * Author: Paolo Bonzini <pbonzini@redhat.com> + */ + +#include <qemu/osdep.h> +#include <qemu/sys_membarrier.h> +#include <qemu/error-report.h> + +#ifdef CONFIG_LINUX +#include <linux/membarrier.h> +#include <sys/syscall.h> + +static int +membarrier(int cmd, int flags) +{ + return syscall(__NR_membarrier, cmd, flags); +} +#endif + +void smp_mb_global(void) +{ +#if defined CONFIG_WIN32 + FlushProcessWriteBuffers(); +#elif defined CONFIG_LINUX + membarrier(MEMBARRIER_CMD_SHARED, 0); +#else +#error --enable-membarrier is not supported on this operating system. +#endif +} + +void smp_mb_global_init(void) +{ +#ifdef CONFIG_LINUX + int ret = membarrier(MEMBARRIER_CMD_QUERY, 0); + if (ret < 0) { + error_report("This QEMU binary requires the membarrier system call."); + error_report("Please upgrade your system to a newer version of Linux"); + exit(1); + } + if (!(ret & MEMBARRIER_CMD_SHARED)) { + error_report("This QEMU binary requires MEMBARRIER_CMD_SHARED support."); + error_report("Please upgrade your system to a newer version of Linux"); + exit(1); + } +#endif +} |