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Date:   Sun, 29 Apr 2018 09:51:27 +0200
From:   Martin Schwidefsky <schwidefsky@de.ibm.com>
To:     Christian Borntraeger <borntraeger@de.ibm.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        David Hildenbrand <david@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Radim =?UTF-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: [PATCH 4.4 12/50] KVM: s390: wire up bpb feature
In-Reply-To: <f8e1244f-d5b8-1eb9-4e71-fb4b0dd7d610@de.ibm.com>
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        <20180427151715.GA3876@kroah.com>
        <20180427154650.GA15121@kroah.com>
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On Fri, 27 Apr 2018 17:53:46 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 04/27/2018 05:46 PM, Greg Kroah-Hartman wrote:
> > On Fri, Apr 27, 2018 at 05:17:15PM +0200, Greg Kroah-Hartman wrote:  
> >> On Fri, Apr 27, 2018 at 05:10:04PM +0200, Christian Borntraeger wrote:  
> >>>
> >>>
> >>> On 04/27/2018 03:58 PM, Greg Kroah-Hartman wrote:  
> >>>> 4.4-stable review patch.  If anyone has any objections, please let me know.
> >>>>
> >>>> ------------------
> >>>>
> >>>> From: Martin Schwidefsky <schwidefsky@de.ibm.com>
> >>>>
> >>>>
> >>>> From: Christian Borntraeger <borntraeger@de.ibm.com>  
> >>
> >> Ick, that is wrong right there, my scripts messed up, this should not
> >> have 2 author lines :(
> >>
> >> I'll go look at all of these, odds are it made the same error
> >> everywhere...  
> > 
> > Yes, I've now fixed that up in the queue.  
> 
> As this patch backport was also functionally incorrect and Martin is already away
> do you want me to send an updated version?

Checked my 4.4 backport git branch and indeed the hunk is misplaced.
Sometime I wonder about the patch tool and the hickups it can produce.

My take on the replacement patch looks as follows:

---
From 82f20b6237a8d04378c8f4a1614bf32a6c8d8a8b Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Wed, 17 Jan 2018 14:44:34 +0100
Subject: [PATCH 03/18] KVM: s390: wire up bpb feature
MIME-Version: 1.0
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[ Upstream commit 35b3fde6203b932b2b1a5b53b3d8808abc9c4f60 ]

The new firmware interfaces for branch prediction behaviour changes
are transparently available for the guest. Nevertheless, there is
new state attached that should be migrated and properly resetted.
Provide a mechanism for handling reset, migration and VSIE.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[Changed capability number to 152. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  3 ++-
 arch/s390/include/uapi/asm/kvm.h |  3 +++
 arch/s390/kvm/kvm-s390.c         | 12 ++++++++++++
 include/uapi/linux/kvm.h         |  1 +
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index e9a983f40a24..7d9c5917da2b 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -136,7 +136,8 @@ struct kvm_s390_sie_block {
 	__u16	ipa;			/* 0x0056 */
 	__u32	ipb;			/* 0x0058 */
 	__u32	scaoh;			/* 0x005c */
-	__u8	reserved60;		/* 0x0060 */
+#define FPF_BPBC 	0x20
+	__u8	fpf;			/* 0x0060 */
 	__u8	ecb;			/* 0x0061 */
 	__u8    ecb2;                   /* 0x0062 */
 #define ECB3_AES 0x04
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index ef1a5fcc6c66..3aec52253c04 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -151,6 +151,7 @@ struct kvm_guest_debug_arch {
 #define KVM_SYNC_ARCH0  (1UL << 4)
 #define KVM_SYNC_PFAULT (1UL << 5)
 #define KVM_SYNC_VRS    (1UL << 6)
+#define KVM_SYNC_BPBC	(1UL << 10)
 /* definition of registers in kvm_run */
 struct kvm_sync_regs {
 	__u64 prefix;	/* prefix register */
@@ -168,6 +169,8 @@ struct kvm_sync_regs {
 	__u64 vrs[32][2];	/* vector registers */
 	__u8  reserved[512];	/* for future vector expansion */
 	__u32 fpc;	/* only valid with vector registers */
+	__u8 bpbc : 1;		/* bp mode */
+	__u8 reserved2 : 7;
 };
 
 #define KVM_REG_S390_TODPR	(KVM_REG_S390 | KVM_REG_SIZE_U32 | 0x1)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 23e3f5d77a24..ca03c847127a 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -257,6 +257,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_S390_VECTOR_REGISTERS:
 		r = MACHINE_HAS_VX;
 		break;
+	case KVM_CAP_S390_BPB:
+		r = test_facility(82);
+		break;
 	default:
 		r = 0;
 	}
@@ -1262,6 +1265,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 				    KVM_SYNC_CRS |
 				    KVM_SYNC_ARCH0 |
 				    KVM_SYNC_PFAULT;
+	if (test_kvm_facility(vcpu->kvm, 82))
+		vcpu->run->kvm_valid_regs |= KVM_SYNC_BPBC;
 	if (test_kvm_facility(vcpu->kvm, 129))
 		vcpu->run->kvm_valid_regs |= KVM_SYNC_VRS;
 
@@ -1327,6 +1332,7 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
 	current->thread.fpu.fpc = 0;
 	vcpu->arch.sie_block->gbea = 1;
 	vcpu->arch.sie_block->pp = 0;
+	vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
 	vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
 	kvm_clear_async_pf_completion_queue(vcpu);
 	if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
@@ -2145,6 +2151,11 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 		if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
 			kvm_clear_async_pf_completion_queue(vcpu);
 	}
+	if ((kvm_run->kvm_dirty_regs & KVM_SYNC_BPBC) &&
+	    test_kvm_facility(vcpu->kvm, 82)) {
+		vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
+		vcpu->arch.sie_block->fpf |= kvm_run->s.regs.bpbc ? FPF_BPBC : 0;
+	}
 	kvm_run->kvm_dirty_regs = 0;
 }
 
@@ -2162,6 +2173,7 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	kvm_run->s.regs.pft = vcpu->arch.pfault_token;
 	kvm_run->s.regs.pfs = vcpu->arch.pfault_select;
 	kvm_run->s.regs.pfc = vcpu->arch.pfault_compare;
+	kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
 }
 
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 03f3618612aa..376d0ab5b9f2 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -831,6 +831,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_GUEST_DEBUG_HW_WPS 120
 #define KVM_CAP_SPLIT_IRQCHIP 121
 #define KVM_CAP_IOEVENTFD_ANY_LENGTH 122
+#define KVM_CAP_S390_BPB 152
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.13.5