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@xxxxxxxxxxxxx>
---
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.
--
Thanks,
David / dhildenb
