kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/arch/s390/kvm/diag.c
..
..
@@ -2,7 +2,7 @@
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2
 /*
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  * handling diagnose instructions
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  *
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- * Copyright IBM Corp. 2008, 2011
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+ * Copyright IBM Corp. 2008, 2020
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  *
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  *    Author(s): Carsten Otte <cotte@de.ibm.com>
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  *               Christian Borntraeger <borntraeger@de.ibm.com>
..
..
@@ -10,7 +10,6 @@
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10
 
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 #include <linux/kvm.h>
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 #include <linux/kvm_host.h>
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-#include <asm/pgalloc.h>
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 #include <asm/gmap.h>
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 #include <asm/virtio-ccw.h>
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 #include "kvm-s390.h"
..
..
@@ -158,14 +157,28 @@
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157
 
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 	tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
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 	vcpu->stat.diagnose_9c++;
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-	VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d", tid);
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160
 
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+	/* yield to self */
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 	if (tid == vcpu->vcpu_id)
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-		return 0;
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+		goto no_yield;
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164
 
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+	/* yield to invalid */
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 	tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid);
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-	if (tcpu)
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-		kvm_vcpu_yield_to(tcpu);
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+	if (!tcpu)
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+		goto no_yield;
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+
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+	/* target already running */
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+	if (READ_ONCE(tcpu->cpu) >= 0)
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+		goto no_yield;
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+
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+	if (kvm_vcpu_yield_to(tcpu) <= 0)
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+		goto no_yield;
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+
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+	VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
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+	return 0;
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+no_yield:
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+	VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
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+	vcpu->stat.diagnose_9c_ignored++;
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 	return 0;
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183
 }
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184
 
..
..
@@ -187,6 +200,10 @@
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 		return -EOPNOTSUPP;
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 	}
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202
 
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+	/*
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+	 * no need to check the return value of vcpu_stop as it can only have
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+	 * an error for protvirt, but protvirt means user cpu state
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+	 */
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 	if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
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 		kvm_s390_vcpu_stop(vcpu);
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 	vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;