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s390/kvm: Provide a way to prevent reentering SIE
Lets provide functions to prevent KVM from reentering SIE and to kick cpus out of SIE. We cannot use the common kvm_vcpu_kick code, since we need to kick out guests in places that hold architecture specific locks (e.g. pgste lock) which might be necessary on the other cpus - so no waiting possible. So lets provide a bit in a private field of the sie control block that acts as a gate keeper, after we claimed we are in SIE. Please note that we do not reuse prog0c, since we want to access that bit without atomic ops. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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5 changed files with 40 additions and 2 deletions
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@ -71,7 +71,10 @@ struct kvm_s390_sie_block {
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__u8 reserved08[4]; /* 0x0008 */
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#define PROG_IN_SIE (1<<0)
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__u32 prog0c; /* 0x000c */
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__u8 reserved10[24]; /* 0x0010 */
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__u8 reserved10[16]; /* 0x0010 */
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#define PROG_BLOCK_SIE 0x00000001
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atomic_t prog20; /* 0x0020 */
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__u8 reserved24[4]; /* 0x0024 */
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__u64 cputm; /* 0x0028 */
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__u64 ckc; /* 0x0030 */
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__u64 epoch; /* 0x0038 */
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@ -163,6 +163,7 @@ int main(void)
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DEFINE(__THREAD_trap_tdb, offsetof(struct task_struct, thread.trap_tdb));
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DEFINE(__GMAP_ASCE, offsetof(struct gmap, asce));
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DEFINE(__SIE_PROG0C, offsetof(struct kvm_s390_sie_block, prog0c));
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DEFINE(__SIE_PROG20, offsetof(struct kvm_s390_sie_block, prog20));
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#endif /* CONFIG_32BIT */
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return 0;
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}
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@ -958,7 +958,9 @@ sie_loop:
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lctlg %c1,%c1,__GMAP_ASCE(%r14) # load primary asce
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sie_gmap:
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lg %r14,__SF_EMPTY(%r15) # get control block pointer
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oi __SIE_PROG0C+3(%r14),1 # we are in SIE now
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oi __SIE_PROG0C+3(%r14),1 # we are going into SIE now
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tm __SIE_PROG20+3(%r14),1 # last exit...
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jnz sie_done
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LPP __SF_EMPTY(%r15) # set guest id
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sie 0(%r14)
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sie_done:
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@ -454,6 +454,34 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
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return 0;
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}
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void s390_vcpu_block(struct kvm_vcpu *vcpu)
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{
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atomic_set_mask(PROG_BLOCK_SIE, &vcpu->arch.sie_block->prog20);
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}
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void s390_vcpu_unblock(struct kvm_vcpu *vcpu)
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{
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atomic_clear_mask(PROG_BLOCK_SIE, &vcpu->arch.sie_block->prog20);
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}
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/*
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* Kick a guest cpu out of SIE and wait until SIE is not running.
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* If the CPU is not running (e.g. waiting as idle) the function will
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* return immediately. */
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void exit_sie(struct kvm_vcpu *vcpu)
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{
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atomic_set_mask(CPUSTAT_STOP_INT, &vcpu->arch.sie_block->cpuflags);
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while (vcpu->arch.sie_block->prog0c & PROG_IN_SIE)
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cpu_relax();
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}
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/* Kick a guest cpu out of SIE and prevent SIE-reentry */
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void exit_sie_sync(struct kvm_vcpu *vcpu)
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{
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s390_vcpu_block(vcpu);
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exit_sie(vcpu);
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}
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int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
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{
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/* kvm common code refers to this, but never calls it */
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@ -133,6 +133,10 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu);
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/* implemented in kvm-s390.c */
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int kvm_s390_vcpu_store_status(struct kvm_vcpu *vcpu,
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unsigned long addr);
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void s390_vcpu_block(struct kvm_vcpu *vcpu);
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void s390_vcpu_unblock(struct kvm_vcpu *vcpu);
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void exit_sie(struct kvm_vcpu *vcpu);
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void exit_sie_sync(struct kvm_vcpu *vcpu);
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/* implemented in diag.c */
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int kvm_s390_handle_diag(struct kvm_vcpu *vcpu);
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