| Message ID | 20211008203112.1979843-6-farman@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Improvements to SIGP handling [KVM] | expand |
On 08.10.21 22:31, Eric Farman wrote: > A SIGP RESTART is a special animal, in that it directs the > destination CPU to perform the restart operation. This is > basically the loading of the Restart PSW and letting it take > over, but a stopped CPU must first be made operating for this > to work correctly. > > As this can take a moment, let's leave a reminder that this > SIGP is being processed, such that the SIGP SENSE logic > (which is not handled in userspace) can return CC=2 instead > of CC=1 (and STOPPED) until the CPU is started. > > Signed-off-by: Eric Farman <farman@linux.ibm.com> > --- > arch/s390/include/asm/kvm_host.h | 1 + > arch/s390/kvm/kvm-s390.c | 1 + > arch/s390/kvm/sigp.c | 17 +++++++++++++++++ > 3 files changed, 19 insertions(+) > > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h > index a604d51acfc8..536f174c5e81 100644 > --- a/arch/s390/include/asm/kvm_host.h > +++ b/arch/s390/include/asm/kvm_host.h > @@ -746,6 +746,7 @@ struct kvm_vcpu_arch { > __u64 cputm_start; > bool gs_enabled; > bool skey_enabled; > + bool sigp_restart; > struct kvm_s390_pv_vcpu pv; > union diag318_info diag318_info; > }; > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 6a6dd5e1daf6..33d71fa42d68 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -4603,6 +4603,7 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu) > } > > kvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED); > + vcpu->arch.sigp_restart = 0; > /* > * The real PSW might have changed due to a RESTART interpreted by the > * ultravisor. We block all interrupts and let the next sie exit > diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c > index c64e37f4347d..5a21354d0265 100644 > --- a/arch/s390/kvm/sigp.c > +++ b/arch/s390/kvm/sigp.c > @@ -27,6 +27,8 @@ static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu, > ext_call_pending = kvm_s390_ext_call_pending(dst_vcpu); > if (!stopped && !ext_call_pending) > rc = SIGP_CC_ORDER_CODE_ACCEPTED; > + else if (stopped && dst_vcpu->arch.sigp_restart) > + rc = SIGP_CC_BUSY; > else { > *reg &= 0xffffffff00000000UL; > if (ext_call_pending) > @@ -385,6 +387,18 @@ static int handle_sigp_order_in_user_space(struct kvm_vcpu *vcpu, u8 order_code, > return 1; > } > > +static void handle_sigp_restart(struct kvm_vcpu *vcpu, u16 cpu_addr) > +{ > + struct kvm_vcpu *dst_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr); > + > + /* Ignore SIGP Restart to non-existent CPUs */ > + if (!dst_vcpu) > + return; > + > + if (is_vcpu_stopped(dst_vcpu)) > + dst_vcpu->arch.sigp_restart = 1; > +} > + > static int handle_sigp_order_is_blocked(struct kvm_vcpu *vcpu, u8 order_code, > u16 cpu_addr) > { > @@ -443,6 +457,9 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu) > if (handle_sigp_order_is_blocked(vcpu, order_code, cpu_addr)) > return 0; > > + if (order_code == SIGP_RESTART) > + handle_sigp_restart(vcpu, cpu_addr); > + > if (handle_sigp_order_in_user_space(vcpu, order_code, cpu_addr)) > return -EOPNOTSUPP; > > Okay, staring at this, I think we really might just let user space indicate SIGP as busy/!busy. Will take a lot of magic out of this code. My 2 cents.
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index a604d51acfc8..536f174c5e81 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -746,6 +746,7 @@ struct kvm_vcpu_arch { __u64 cputm_start; bool gs_enabled; bool skey_enabled; + bool sigp_restart; struct kvm_s390_pv_vcpu pv; union diag318_info diag318_info; }; diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 6a6dd5e1daf6..33d71fa42d68 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -4603,6 +4603,7 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu) } kvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED); + vcpu->arch.sigp_restart = 0; /* * The real PSW might have changed due to a RESTART interpreted by the * ultravisor. We block all interrupts and let the next sie exit diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c index c64e37f4347d..5a21354d0265 100644 --- a/arch/s390/kvm/sigp.c +++ b/arch/s390/kvm/sigp.c @@ -27,6 +27,8 @@ static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu, ext_call_pending = kvm_s390_ext_call_pending(dst_vcpu); if (!stopped && !ext_call_pending) rc = SIGP_CC_ORDER_CODE_ACCEPTED; + else if (stopped && dst_vcpu->arch.sigp_restart) + rc = SIGP_CC_BUSY; else { *reg &= 0xffffffff00000000UL; if (ext_call_pending) @@ -385,6 +387,18 @@ static int handle_sigp_order_in_user_space(struct kvm_vcpu *vcpu, u8 order_code, return 1; } +static void handle_sigp_restart(struct kvm_vcpu *vcpu, u16 cpu_addr) +{ + struct kvm_vcpu *dst_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr); + + /* Ignore SIGP Restart to non-existent CPUs */ + if (!dst_vcpu) + return; + + if (is_vcpu_stopped(dst_vcpu)) + dst_vcpu->arch.sigp_restart = 1; +} + static int handle_sigp_order_is_blocked(struct kvm_vcpu *vcpu, u8 order_code, u16 cpu_addr) { @@ -443,6 +457,9 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu) if (handle_sigp_order_is_blocked(vcpu, order_code, cpu_addr)) return 0; + if (order_code == SIGP_RESTART) + handle_sigp_restart(vcpu, cpu_addr); + if (handle_sigp_order_in_user_space(vcpu, order_code, cpu_addr)) return -EOPNOTSUPP;
A SIGP RESTART is a special animal, in that it directs the destination CPU to perform the restart operation. This is basically the loading of the Restart PSW and letting it take over, but a stopped CPU must first be made operating for this to work correctly. As this can take a moment, let's leave a reminder that this SIGP is being processed, such that the SIGP SENSE logic (which is not handled in userspace) can return CC=2 instead of CC=1 (and STOPPED) until the CPU is started. Signed-off-by: Eric Farman <farman@linux.ibm.com> --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/kvm-s390.c | 1 + arch/s390/kvm/sigp.c | 17 +++++++++++++++++ 3 files changed, 19 insertions(+)