kvm: i386: allow TSC to differ by NTP correction bounds without TSC scaling
PATCH 1/1 kvm: i386: allow TSC to differ by NTP correction bounds without TSC scaling
The Linux TSC calibration procedure is subject to small variations (its common to see +-1 kHz difference between reboots on a given CPU, for example).
So migrating a guest between two hosts with identical processor can fail, in case of a small variation in calibrated TSC between them.
Allow a conservative 250ppm error between host TSC and VM TSC frequencies, rather than requiring an exact match. NTP daemon in the guest can correct this difference.
Also change migration to accept this bound.
target/i386/kvm.c +27 -6
@@ -739,23 +739,44 @@ static int kvm_arch_set_tsc_khz(CPUState *cs) {X86CPU *cpu =X86_CPU (cs);CPUX86State *env = &cpu->env; -int r; +int r, cur_freq; +bool set_ioctl = false;if (!env->tsc_khz) {return 0 ; } - r =kvm_check_extension (cs->kvm_state,KVM_CAP_TSC_CONTROL ) ? + cur_freq =kvm_check_extension (cs->kvm_state,KVM_CAP_GET_TSC_KHZ ) ? +kvm_vcpu_ioctl (cs,KVM_GET_TSC_KHZ ) : -ENOTSUP ; + +/* +* If TSC scaling is supported, attempt to set TSC frequency. +*/ +if (kvm_check_extension (cs->kvm_state,KVM_CAP_TSC_CONTROL )) { + set_ioctl = true; + } + +/* +* If desired TSC frequency is within bounds of NTP correction, +* attempt to set TSC frequency. +*/ +if (cur_freq != -ENOTSUP &&freq_within_bounds (cur_freq, env->tsc_khz)) { + set_ioctl = true; + } + + r = set_ioctl ?kvm_vcpu_ioctl (cs,KVM_SET_TSC_KHZ , env->tsc_khz) : -ENOTSUP ; +if (r <0 ) {/* When KVM_SET_TSC_KHZ fails, it's an error only if the current * TSC frequency doesn't match the one we want. */ -int cur_freq =kvm_check_extension (cs->kvm_state,KVM_CAP_GET_TSC_KHZ ) ? -kvm_vcpu_ioctl (cs,KVM_GET_TSC_KHZ ) : - -ENOTSUP ; -if (cur_freq <=0 || cur_freq != env->tsc_khz) { + cur_freq =kvm_check_extension (cs->kvm_state,KVM_CAP_GET_TSC_KHZ ) ? +kvm_vcpu_ioctl (cs,KVM_GET_TSC_KHZ ) : + -ENOTSUP ; +if (cur_freq <=0 || (cur_freq != env->tsc_khz && + !freq_within_bounds (cur_freq, env->tsc_khz))) { warn_report("TSC frequency mismatch between " "VM (%" PRId64 " kHz) and host (%d kHz), " "and TSC scaling unavailable",
target/i386/kvm_i386.h +16 -0
@@ -47,4 +47,20 @@ bool kvm_has_x2apic_api(void);bool kvm_hv_vpindex_settable (void ); +/* +* Check whether target_freq is within conservative +* ntp correctable bounds (250ppm) of freq +*/ +static inline bool freq_within_bounds (int freq,int target_freq) +{ +int max_freq = freq + (freq *250 /1000000 ); +int min_freq = freq - (freq *250 /1000000 ); + +if (target_freq >= min_freq && target_freq <= max_freq) { +return true; + } + +return false; +} +#endif
target/i386/machine.c +1 -1
@@ -300,7 +300,7 @@ static int cpu_post_load(void *opaque, int version_id)int i;if (env->tsc_khz && env->user_tsc_khz && - env->tsc_khz != env->user_tsc_khz) { + !freq_within_bounds (env->tsc_khz, env->user_tsc_khz)) {error_report ("Mismatch between user-specified TSC frequency and " "migrated TSC frequency" );return -EINVAL ;
PATCH v2 1/1 kvm: i386: allow TSC to differ by NTP correction bounds without TSC scaling
The Linux TSC calibration procedure is subject to small variations (its common to see +-1 kHz difference between reboots on a given CPU, for example).
So migrating a guest between two hosts with identical processor can fail, in case of a small variation in calibrated TSC between them.
Allow a conservative 250ppm error between host TSC and VM TSC frequencies, rather than requiring an exact match. NTP daemon in the guest can correct this difference.
Also change migration to accept this bound.
KVM_SET_TSC_KHZ depends on a kernel interface change. Without this change, the behaviour remains the same: in case of a different frequency between host and VM, KVM_SET_TSC_KHZ will fail and QEMU will exit.
---
v2: ensure behaviour is unchanged for older kernels and
improve changelogs (Paolo)
target/i386/kvm.c +41 -5
@@ -735,26 +735,62 @@ static bool hyperv_enabled(X86CPU *cpu) cpu->hyperv_features || cpu->hyperv_passthrough); } +/* +* Check whether target_freq is within conservative +* ntp correctable bounds (250ppm) of freq +*/ +static inline bool freq_within_bounds (int freq,int target_freq) +{ +int max_freq = freq + (freq *250 /1000000 ); +int min_freq = freq - (freq *250 /1000000 ); + +if (target_freq >= min_freq && target_freq <= max_freq) { +return true; + } + +return false; +} +static int kvm_arch_set_tsc_khz (CPUState *cs) {X86CPU *cpu =X86_CPU (cs);CPUX86State *env = &cpu->env; -int r; +int r, cur_freq; +bool set_ioctl = false;if (!env->tsc_khz) {return 0 ; } - r =kvm_check_extension (cs->kvm_state,KVM_CAP_TSC_CONTROL ) ? + cur_freq =kvm_check_extension (cs->kvm_state,KVM_CAP_GET_TSC_KHZ ) ? +kvm_vcpu_ioctl (cs,KVM_GET_TSC_KHZ ) : -ENOTSUP ; + +/* +* If TSC scaling is supported, attempt to set TSC frequency. +*/ +if (kvm_check_extension (cs->kvm_state,KVM_CAP_TSC_CONTROL )) { + set_ioctl = true; + } + +/* +* If desired TSC frequency is within bounds of NTP correction, +* attempt to set TSC frequency. +*/ +if (cur_freq != -ENOTSUP &&freq_within_bounds (cur_freq, env->tsc_khz)) { + set_ioctl = true; + } + + r = set_ioctl ?kvm_vcpu_ioctl (cs,KVM_SET_TSC_KHZ , env->tsc_khz) : -ENOTSUP ; +if (r <0 ) {/* When KVM_SET_TSC_KHZ fails, it's an error only if the current * TSC frequency doesn't match the one we want. */ -int cur_freq =kvm_check_extension (cs->kvm_state,KVM_CAP_GET_TSC_KHZ ) ? -kvm_vcpu_ioctl (cs,KVM_GET_TSC_KHZ ) : - -ENOTSUP ; + cur_freq =kvm_check_extension (cs->kvm_state,KVM_CAP_GET_TSC_KHZ ) ? +kvm_vcpu_ioctl (cs,KVM_GET_TSC_KHZ ) : + -ENOTSUP ;if (cur_freq <=0 || cur_freq != env->tsc_khz) {warn_report ("TSC frequency mismatch between " "VM (%" PRId64 " kHz) and host (%d kHz), "
Patchew URL: https://patchew.org/QEMU/[email protected]/
Patchew URL: https://patchew.org/QEMU/[email protected]/
Hi,
This series failed the asan build test. Please find the testing commands and their output below. If you have Docker installed, you can probably reproduce it locally.
=== TEST SCRIPT BEGIN ===
#!/bin/bash
export ARCH=x86_64
make docker-image-fedora V=1 NETWORK=1
time make docker-test-debug@fedora TARGET_LIST=x86_64-softmmu J=14 NETWORK=1 === TEST SCRIPT END ===
GEN tools/virtiofsd/50-qemu-virtiofsd.json CC contrib/vhost-user-input/main.o LINK tests/qemu-iotests/socket_scm_helper /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) GEN docs/interop/qemu-qmp-ref.html GEN docs/interop/qemu-qmp-ref.txt GEN docs/interop/qemu-qmp-ref.7 --- AR libqemuutil.a LINK elf2dmp CC qemu-img.o /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) LINK qemu-io /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) LINK qemu-edid BUILD pc-bios/optionrom/linuxboot_dma.img BUILD pc-bios/optionrom/pvh.img --- BUILD pc-bios/optionrom/pvh.raw SIGN pc-bios/optionrom/pvh.bin LINK fsdev/virtfs-proxy-helper
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
LINK scsi/qemu-pr-helper/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
LINK qemu-bridge-helper/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
AR libvhost-user.a/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
GEN docs/interop/qemu-ga-ref.html GEN docs/interop/qemu-ga-ref.txt GEN docs/interop/qemu-ga-ref.7 LINK qemu-keymap
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
LINK ivshmem-client
LINK ivshmem-server/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
LINK qemu-nbd/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
LINK qemu-storage-daemon LINK virtiofsd LINK vhost-user-input LINK qemu-ga
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o) /usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
LINK qemu-img/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
GEN x86_64-softmmu/hmp-commands.h
GEN x86_64-softmmu/hmp-commands-info.h
GEN x86_64-softmmu/config-devices.h
---
CC x86_64-softmmu/qtest.o
CC x86_64-softmmu/memory.o
CC x86_64-softmmu/memory_mapping.o
/tmp/qemu-test/src/fpu/softfloat.c:3365:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
absZ &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:3423:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
absZ0 &= ~ ( ( (uint64_t) ( absZ1<<1 ) == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:3483:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
absZ0 &= ~(((uint64_t)(absZ1<<1) == 0) & roundNearestEven);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:3606:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
zSig &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:3760:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
zSig &= ~ ( ( ( roundBits ^ 0x200 ) == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:3987:21: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
~ ( ( (uint64_t) ( zSig1<<1 ) == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:4003:22: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
zSig0 &= ~ ( ( (uint64_t) ( zSig1<<1 ) == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
/tmp/qemu-test/src/fpu/softfloat.c:4273:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
zSig1 &= ~ ( ( zSig2 + zSig2 == 0 ) & roundNearestEven );
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!8 errors generated.
make[1]: *** [/tmp/qemu-test/src/rules.mak:69: fpu/softfloat.o] Error 1 make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:527: x86_64-softmmu/all] Error 2 Traceback (most recent call last):
File "./tests/docker/docker.py", line 669, in <module>
sys.exit(main())
---
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['sudo', '-n', 'docker', 'run', '--label', 'com.qemu.instance.uuid=b4a5184fc16644b0914afc022957a9c0', '-u', '1001', '--security-opt', 'seccomp=unconfined', '--rm', '-e', 'TARGET_LIST=x86_64-softmmu', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=14', '-e', 'DEBUG=', '-e', 'SHOW_ENV=', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/home/patchew/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-zgpzucz9/src/docker-src.2020-06-16-17.29.39.13804:/var/tmp/qemu:z,ro', 'qemu:fedora', '/var/tmp/qemu/run', 'test-debug']' returned non-zero exit status 2. filter=--filter=label=com.qemu.instance.uuid=b4a5184fc16644b0914afc022957a9c0
make[1]: *** [docker-run] Error 1
make[1]: Leaving directory `/var/tmp/patchew-tester-tmp-zgpzucz9/src'
make: *** [docker-run-test-debug@fedora] Error 2
real 6m19.842s
user 0m8.530s
The full log is available at
http://patchew.org/logs/[email protected]/testing.asan/?type=message.
---
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