The name "iothread" is overloaded. Use the term Big QEMU Lock (BQL)
instead, it is already widely used and unambiguous.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-4-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().
The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.
The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)
There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Currently, a vm in the suspended state is not completely stopped. The VCPUs
have been paused, but the cpu clock still runs, and runstate notifiers for
the transition to stopped have not been called. This causes problems for
live migration. Stale cpu timers_state is saved to the migration stream,
causing time errors in the guest when it wakes from suspend, and state that
would have been modified by runstate notifiers is wrong.
Modify vm_stop to completely stop the vm if the current state is suspended,
transition to RUN_STATE_PAUSED, and remember that the machine was suspended.
Modify vm_start to restore the suspended state.
This affects all callers of vm_stop and vm_start, notably, the qapi stop and
cont commands:
old behavior:
RUN_STATE_SUSPENDED --> stop --> RUN_STATE_SUSPENDED
new behavior:
RUN_STATE_SUSPENDED --> stop --> RUN_STATE_PAUSED
RUN_STATE_PAUSED --> cont --> RUN_STATE_SUSPENDED
For example:
(qemu) info status
VM status: paused (suspended)
(qemu) stop
(qemu) info status
VM status: paused
(qemu) system_wakeup
Error: Unable to wake up: guest is not in suspended state
(qemu) cont
(qemu) info status
VM status: paused (suspended)
(qemu) system_wakeup
(qemu) info status
VM status: running
Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1704312341-66640-3-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>
From CPUState.nr_cores' comment, it represents "number of cores within
this CPU package".
After 003f230e37 ("machine: Tweak the order of topology members in
struct CpuTopology"), the meaning of smp.cores changed to "the number of
cores in one die", but this commit missed to change CPUState.nr_cores'
calculation, so that CPUState.nr_cores became wrong and now it
misses to consider numbers of clusters and dies.
At present, only i386 is using CPUState.nr_cores.
But as for i386, which supports die level, the uses of CPUState.nr_cores
are very confusing:
Early uses are based on the meaning of "cores per package" (before die
is introduced into i386), and later uses are based on "cores per die"
(after die's introduction).
This difference is due to that commit a94e142899 ("target/i386: Add
CPUID.1F generation support for multi-dies PCMachine") misunderstood
that CPUState.nr_cores means "cores per die" when calculated
CPUID.1FH.01H:EBX. After that, the changes in i386 all followed this
wrong understanding.
With the influence of 003f230e37 and a94e142899, for i386 currently
the result of CPUState.nr_cores is "cores per die", thus the original
uses of CPUState.cores based on the meaning of "cores per package" are
wrong when multiple dies exist:
1. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.01H:EBX[bits 23:16] is
incorrect because it expects "cpus per package" but now the
result is "cpus per die".
2. In cpu_x86_cpuid() of target/i386/cpu.c, for all leaves of CPUID.04H:
EAX[bits 31:26] is incorrect because they expect "cpus per package"
but now the result is "cpus per die". The error not only impacts the
EAX calculation in cache_info_passthrough case, but also impacts other
cases of setting cache topology for Intel CPU according to cpu
topology (specifically, the incoming parameter "num_cores" expects
"cores per package" in encode_cache_cpuid4()).
3. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.0BH.01H:EBX[bits
15:00] is incorrect because the EBX of 0BH.01H (core level) expects
"cpus per package", which may be different with 1FH.01H (The reason
is 1FH can support more levels. For QEMU, 1FH also supports die,
1FH.01H:EBX[bits 15:00] expects "cpus per die").
4. In cpu_x86_cpuid() of target/i386/cpu.c, when CPUID.80000001H is
calculated, here "cpus per package" is expected to be checked, but in
fact, now it checks "cpus per die". Though "cpus per die" also works
for this code logic, this isn't consistent with AMD's APM.
5. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.80000008H:ECX expects
"cpus per package" but it obtains "cpus per die".
6. In simulate_rdmsr() of target/i386/hvf/x86_emu.c, in
kvm_rdmsr_core_thread_count() of target/i386/kvm/kvm.c, and in
helper_rdmsr() of target/i386/tcg/sysemu/misc_helper.c,
MSR_CORE_THREAD_COUNT expects "cpus per package" and "cores per
package", but in these functions, it obtains "cpus per die" and
"cores per die".
On the other hand, these uses are correct now (they are added in/after
a94e142899):
1. In cpu_x86_cpuid() of target/i386/cpu.c, topo_info.cores_per_die
meets the actual meaning of CPUState.nr_cores ("cores per die").
2. In cpu_x86_cpuid() of target/i386/cpu.c, vcpus_per_socket (in CPUID.
04H's calculation) considers number of dies, so it's correct.
3. In cpu_x86_cpuid() of target/i386/cpu.c, CPUID.1FH.01H:EBX[bits
15:00] needs "cpus per die" and it gets the correct result, and
CPUID.1FH.02H:EBX[bits 15:00] gets correct "cpus per package".
When CPUState.nr_cores is correctly changed to "cores per package" again
, the above errors will be fixed without extra work, but the "currently"
correct cases will go wrong and need special handling to pass correct
"cpus/cores per die" they want.
Fix CPUState.nr_cores' calculation to fit the original meaning "cores
per package", as well as changing calculation of topo_info.cores_per_die,
vcpus_per_socket and CPUID.1FH.
Fixes: a94e142899 ("target/i386: Add CPUID.1F generation support for multi-dies PCMachine")
Fixes: 003f230e37 ("machine: Tweak the order of topology members in struct CpuTopology")
Signed-off-by: Zhuocheng Ding <zhuocheng.ding@intel.com>
Co-developed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20231024090323.1859210-4-zhao1.liu@linux.intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Introduce cpu_exec_reset_hold() which call an accelerator
specific AccelOpsClass::cpu_reset_hold() handler.
Define a stub on TCG user emulation, because CPU reset is
irrelevant there.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230918104153.24433-3-philmd@linaro.org>
The softmmu/ directory contains files specific to system
emulation. Rename it as system/. Update meson rules, the
MAINTAINERS file and all the documentation and comments.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231004090629.37473-14-philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
