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Re: [Qemu-devel] [PATCH RFC] s390x: refactor reset/reipl handling
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH RFC] s390x: refactor reset/reipl handling |
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Date: |
Thu, 12 Apr 2018 22:49:21 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 |
On 12/04/2018 21:26, David Hildenbrand wrote:
> Calling pause_all_vcpus()/resume_all_vcpus() from a VCPU thread might
> not be the best idea. As pause_all_vcpus() temporarily drops the qemu
> mutex, two parallel calls to pause_all_vcpus() can be active at a time,
> resulting in a deadlock. (either by two VCPUs or by the main thread and a
> VCPU)
>
> Let's handle it via the main loop instead, as suggested by Paolo. If we
> would have two parallel reset requests by two different VCPUs at the
> same time, the last one would win.
>
> We use the existing ipl device to handle it. The nice side effect is
> that we can get rid of reipl_requested.
>
> This change implies that all reset handling now goes via the common
> path, so "no-reboot" handling is now active for all kinds of reboots.
>
> Let's execute any CPU initialization code on the target CPU using
> run_on_cpu.
>
> Signed-off-by: David Hildenbrand <address@hidden>
> ---
>
> Did only a quick check with TCG. I think this way it is way easier to
> control what is getting reset.
Happy that it went well (there's always some trepidation when suggesting
a refactoring :)). For what I can understand, it looks sane.
Paolo
> hw/s390x/ipl.c | 44 ++++++++++++++++++++++++---
> hw/s390x/ipl.h | 16 ++++++++--
> hw/s390x/s390-virtio-ccw.c | 49 +++++++++++++++++++++++++-----
> include/hw/s390x/s390-virtio-ccw.h | 2 --
> target/s390x/cpu.h | 26 ++++++++++++++++
> target/s390x/diag.c | 61
> +++-----------------------------------
> target/s390x/internal.h | 6 ----
> target/s390x/kvm.c | 2 +-
> 8 files changed, 127 insertions(+), 79 deletions(-)
>
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index fb554ab156..f7589d20f1 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -26,6 +26,7 @@
> #include "qemu/config-file.h"
> #include "qemu/cutils.h"
> #include "qemu/option.h"
> +#include "exec/exec-all.h"
>
> #define KERN_IMAGE_START 0x010000UL
> #define KERN_PARM_AREA 0x010480UL
> @@ -484,11 +485,22 @@ IplParameterBlock *s390_ipl_get_iplb(void)
> return &ipl->iplb;
> }
>
> -void s390_reipl_request(void)
> +void s390_ipl_reset_request(CPUState *cs, enum s390_reset reset_type)
> {
> S390IPLState *ipl = get_ipl_device();
>
> - ipl->reipl_requested = true;
> + if (reset_type == S390_RESET_EXTERNAL || reset_type == S390_RESET_REIPL)
> {
> + /* let's always use CPU 0 */
> + ipl->reset_cpu = NULL;
> + } else {
> + ipl->reset_cpu = cs;
> + }
> + ipl->reset_type = reset_type;
> +
> + if (reset_type != S390_RESET_REIPL) {
> + goto no_reipl;
> + }
> +
> if (ipl->iplb_valid &&
> !ipl->netboot &&
> ipl->iplb.pbt == S390_IPL_TYPE_CCW &&
> @@ -505,7 +517,32 @@ void s390_reipl_request(void)
> ipl->iplb_valid = s390_gen_initial_iplb(ipl);
> }
> }
> +no_reipl:
> qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
> + /* as this is triggered by a CPU, make sure to exit the loop */
> + if (tcg_enabled()) {
> + cpu_loop_exit(cs);
> + }
> +}
> +
> +void s390_ipl_get_reset_request(CPUState **cs, enum s390_reset *reset_type)
> +{
> + S390IPLState *ipl = get_ipl_device();
> +
> + *cs = ipl->reset_cpu;
> + if (!ipl->reset_cpu) {
> + /* use CPU 0 as default */
> + *cs = qemu_get_cpu(0);
> + }
> + *reset_type = ipl->reset_type;
> +}
> +
> +void s390_ipl_clear_reset_request(void)
> +{
> + S390IPLState *ipl = get_ipl_device();
> +
> + ipl->reset_type = S390_RESET_EXTERNAL;
> + ipl->reset_cpu = NULL;
> }
>
> static void s390_ipl_prepare_qipl(S390CPU *cpu)
> @@ -552,11 +589,10 @@ static void s390_ipl_reset(DeviceState *dev)
> {
> S390IPLState *ipl = S390_IPL(dev);
>
> - if (!ipl->reipl_requested) {
> + if (ipl->reset_type != S390_RESET_REIPL) {
> ipl->iplb_valid = false;
> memset(&ipl->iplb, 0, sizeof(IplParameterBlock));
> }
> - ipl->reipl_requested = false;
> }
>
> static void s390_ipl_class_init(ObjectClass *klass, void *data)
> diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
> index 0570d0ad75..102f1ea7af 100644
> --- a/hw/s390x/ipl.h
> +++ b/hw/s390x/ipl.h
> @@ -87,7 +87,17 @@ int s390_ipl_set_loadparm(uint8_t *loadparm);
> void s390_ipl_update_diag308(IplParameterBlock *iplb);
> void s390_ipl_prepare_cpu(S390CPU *cpu);
> IplParameterBlock *s390_ipl_get_iplb(void);
> -void s390_reipl_request(void);
> +
> +enum s390_reset {
> + /* default is a reset not triggered by a CPU e.g. issued by QMP */
> + S390_RESET_EXTERNAL = 0,
> + S390_RESET_REIPL,
> + S390_RESET_MODIFIED_CLEAR,
> + S390_RESET_LOAD_NORMAL,
> +};
> +void s390_ipl_reset_request(CPUState *cs, enum s390_reset reset_type);
> +void s390_ipl_get_reset_request(CPUState **cs, enum s390_reset *reset_type);
> +void s390_ipl_clear_reset_request(void);
>
> #define QIPL_ADDRESS 0xcc
>
> @@ -129,9 +139,11 @@ struct S390IPLState {
> bool enforce_bios;
> IplParameterBlock iplb;
> bool iplb_valid;
> - bool reipl_requested;
> bool netboot;
> QemuIplParameters qipl;
> + /* reset related properties don't have to be migrated or reset */
> + enum s390_reset reset_type;
> + CPUState *reset_cpu;
>
> /*< public >*/
> char *kernel;
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index 435f7c99e7..f625900435 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -93,7 +93,7 @@ static const char *const reset_dev_types[] = {
> "diag288",
> };
>
> -void subsystem_reset(void)
> +static void subsystem_reset(void)
> {
> DeviceState *dev;
> int i;
> @@ -364,17 +364,52 @@ static void s390_cpu_plug(HotplugHandler *hotplug_dev,
> }
> }
>
> +static inline void s390_do_cpu_ipl(CPUState *cs, run_on_cpu_data arg)
> +{
> + S390CPU *cpu = S390_CPU(cs);
> +
> + s390_ipl_prepare_cpu(cpu);
> + s390_cpu_set_state(S390_CPU_STATE_OPERATING, cpu);
> +}
> +
> static void s390_machine_reset(void)
> {
> - S390CPU *ipl_cpu = S390_CPU(qemu_get_cpu(0));
> + enum s390_reset reset_type;
> + CPUState *cs, *t;
>
> + /* get the reset parameters, reset them once done */
> + s390_ipl_get_reset_request(&cs, &reset_type);
> +
> + /* all CPUs are paused and synchronized at this point */
> s390_cmma_reset();
> - qemu_devices_reset();
> - s390_crypto_reset();
>
> - /* all cpus are stopped - configure and start the ipl cpu only */
> - s390_ipl_prepare_cpu(ipl_cpu);
> - s390_cpu_set_state(S390_CPU_STATE_OPERATING, ipl_cpu);
> + switch (reset_type) {
> + case S390_RESET_EXTERNAL:
> + case S390_RESET_REIPL:
> + qemu_devices_reset();
> + s390_crypto_reset();
> +
> + /* configure and start the ipl CPU only */
> + run_on_cpu(cs, s390_do_cpu_ipl, RUN_ON_CPU_NULL);
> + break;
> + case S390_RESET_MODIFIED_CLEAR:
> + CPU_FOREACH(t) {
> + run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
> + }
> + subsystem_reset();
> + s390_crypto_reset();
> + run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
> + break;
> + case S390_RESET_LOAD_NORMAL:
> + CPU_FOREACH(t) {
> + run_on_cpu(t, s390_do_cpu_reset, RUN_ON_CPU_NULL);
> + }
> + subsystem_reset();
> + run_on_cpu(cs, s390_do_cpu_initital_reset, RUN_ON_CPU_NULL);
> + run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
> + break;
> + }
> + s390_ipl_clear_reset_request();
> }
>
> static void s390_machine_device_plug(HotplugHandler *hotplug_dev,
> diff --git a/include/hw/s390x/s390-virtio-ccw.h
> b/include/hw/s390x/s390-virtio-ccw.h
> index ac896e31ea..ab88d49d10 100644
> --- a/include/hw/s390x/s390-virtio-ccw.h
> +++ b/include/hw/s390x/s390-virtio-ccw.h
> @@ -53,6 +53,4 @@ bool cpu_model_allowed(void);
> */
> bool css_migration_enabled(void);
>
> -void subsystem_reset(void);
> -
> #endif
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index 3ee40f08b7..0c2583fd3c 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -686,6 +686,32 @@ static inline uint64_t s390_build_validity_mcic(void)
> return mcic;
> }
>
> +static inline void s390_do_cpu_full_reset(CPUState *cs, run_on_cpu_data arg)
> +{
> + cpu_reset(cs);
> +}
> +
> +static inline void s390_do_cpu_reset(CPUState *cs, run_on_cpu_data arg)
> +{
> + S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
> +
> + scc->cpu_reset(cs);
> +}
> +
> +static inline void s390_do_cpu_initital_reset(CPUState *cs, run_on_cpu_data
> arg)
> +{
> + S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
> +
> + scc->initial_cpu_reset(cs);
> +}
> +
> +static inline void s390_do_cpu_load_normal(CPUState *cs, run_on_cpu_data arg)
> +{
> + S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
> +
> + scc->load_normal(cs);
> +}
> +
>
> /* cpu.c */
> int s390_get_clock(uint8_t *tod_high, uint64_t *tod_low);
> diff --git a/target/s390x/diag.c b/target/s390x/diag.c
> index a755837ad5..ac2c40f363 100644
> --- a/target/s390x/diag.c
> +++ b/target/s390x/diag.c
> @@ -22,51 +22,6 @@
> #include "hw/s390x/ipl.h"
> #include "hw/s390x/s390-virtio-ccw.h"
>
> -static int modified_clear_reset(S390CPU *cpu)
> -{
> - S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
> - CPUState *t;
> -
> - pause_all_vcpus();
> - cpu_synchronize_all_states();
> - CPU_FOREACH(t) {
> - run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
> - }
> - s390_cmma_reset();
> - subsystem_reset();
> - s390_crypto_reset();
> - scc->load_normal(CPU(cpu));
> - cpu_synchronize_all_post_reset();
> - resume_all_vcpus();
> - return 0;
> -}
> -
> -static inline void s390_do_cpu_reset(CPUState *cs, run_on_cpu_data arg)
> -{
> - S390CPUClass *scc = S390_CPU_GET_CLASS(cs);
> -
> - scc->cpu_reset(cs);
> -}
> -
> -static int load_normal_reset(S390CPU *cpu)
> -{
> - S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
> - CPUState *t;
> -
> - pause_all_vcpus();
> - cpu_synchronize_all_states();
> - CPU_FOREACH(t) {
> - run_on_cpu(t, s390_do_cpu_reset, RUN_ON_CPU_NULL);
> - }
> - s390_cmma_reset();
> - subsystem_reset();
> - scc->initial_cpu_reset(CPU(cpu));
> - scc->load_normal(CPU(cpu));
> - cpu_synchronize_all_post_reset();
> - resume_all_vcpus();
> - return 0;
> -}
> -
> int handle_diag_288(CPUS390XState *env, uint64_t r1, uint64_t r3)
> {
> uint64_t func = env->regs[r1];
> @@ -101,6 +56,7 @@ int handle_diag_288(CPUS390XState *env, uint64_t r1,
> uint64_t r3)
>
> void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t
> ra)
> {
> + CPUState *cs = CPU(s390_env_get_cpu(env));
> uint64_t addr = env->regs[r1];
> uint64_t subcode = env->regs[r3];
> IplParameterBlock *iplb;
> @@ -117,22 +73,13 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1,
> uint64_t r3, uintptr_t ra)
>
> switch (subcode) {
> case 0:
> - modified_clear_reset(s390_env_get_cpu(env));
> - if (tcg_enabled()) {
> - cpu_loop_exit(CPU(s390_env_get_cpu(env)));
> - }
> + s390_ipl_reset_request(cs, S390_RESET_MODIFIED_CLEAR);
> break;
> case 1:
> - load_normal_reset(s390_env_get_cpu(env));
> - if (tcg_enabled()) {
> - cpu_loop_exit(CPU(s390_env_get_cpu(env)));
> - }
> + s390_ipl_reset_request(cs, S390_RESET_LOAD_NORMAL);
> break;
> case 3:
> - s390_reipl_request();
> - if (tcg_enabled()) {
> - cpu_loop_exit(CPU(s390_env_get_cpu(env)));
> - }
> + s390_ipl_reset_request(cs, S390_RESET_REIPL);
> break;
> case 5:
> if ((r1 & 1) || (addr & 0x0fffULL)) {
> diff --git a/target/s390x/internal.h b/target/s390x/internal.h
> index d911e84958..e392a02d12 100644
> --- a/target/s390x/internal.h
> +++ b/target/s390x/internal.h
> @@ -273,12 +273,6 @@ static inline hwaddr decode_basedisp_s(CPUS390XState
> *env, uint32_t ipb,
> /* Base/displacement are at the same locations. */
> #define decode_basedisp_rs decode_basedisp_s
>
> -static inline void s390_do_cpu_full_reset(CPUState *cs, run_on_cpu_data arg)
> -{
> - cpu_reset(cs);
> -}
> -
> -
> /* arch_dump.c */
> int s390_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> int cpuid, void *opaque);
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index fb59d92def..b033d53f69 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -1785,7 +1785,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run
> *run)
> ret = handle_intercept(cpu);
> break;
> case KVM_EXIT_S390_RESET:
> - s390_reipl_request();
> + s390_ipl_reset_request(cs, S390_RESET_REIPL);
> break;
> case KVM_EXIT_S390_TSCH:
> ret = handle_tsch(cpu);
>