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FAILED: patch "[PATCH] KVM: s390: do not clobber registers during guest reset/store" failed to apply to 4.14-stable tree

PATCH [email protected] 2 participants 2 messages Feb 9, 2020

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author maintainer
#0 lore raw

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 55680890ea78be0df5e1384989f1be835043c084 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <[email protected]>
Date: Fri, 31 Jan 2020 05:02:00 -0500
Subject: [PATCH] KVM: s390: do not clobber registers during guest reset/store
status

The initial CPU reset clobbers the userspace fpc and the store status ioctl clobbers the guest acrs + fpr. As these calls are only done via ioctl (and not via vcpu_run), no CPU context is loaded, so we can (and must) act directly on the sync regs, not on the thread context.

Cc [email protected]
Fixes e1788bb995be ("KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load")
Fixes 31d8b8d41a7e ("KVM: s390: handle access registers in the run ioctl not in vcpu_put/load")
Signed-off-by Christian Borntraeger <[email protected]>
Reviewed-by David Hildenbrand <[email protected]>
Reviewed-by Cornelia Huck <[email protected]>
Signed-off-by Janosch Frank <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Christian Borntraeger <[email protected]>
arch/s390/kvm/kvm-s390.c +2 -4
index d9e6bf3d54f0..876802894b35 100644
@@ -2860,9 +2860,7 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
 	vcpu->arch.sie_block->gcr[14] = CR14_UNUSED_32 |
 					CR14_UNUSED_33 |
 					CR14_EXTERNAL_DAMAGE_SUBMASK;
-	/* make sure the new fpc will be lazily loaded */
-	save_fpu_regs();
-	current->thread.fpu.fpc = 0;
+	vcpu->run->s.regs.fpc = 0;
 	vcpu->arch.sie_block->gbea = 1;
 	vcpu->arch.sie_block->pp = 0;
 	vcpu->arch.sie_block->fpf &= ~FPF_BPBC;

@@ -4351,7 +4349,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	switch (ioctl) {
 	case KVM_S390_STORE_STATUS:
 		idx = srcu_read_lock(&vcpu->kvm->srcu);
-		r = kvm_s390_vcpu_store_status(vcpu, arg);
+		r = kvm_s390_store_status_unloaded(vcpu, arg);
 		srcu_read_unlock(&vcpu->kvm->srcu, idx);
 		break;
 	case KVM_S390_SET_INITIAL_PSW: {
maintainer
#1 lore raw
Quoted 23 lines · On Sun, Feb 09, 2020 at 01:37:35PM +0100, [email protected] wrote:

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 55680890ea78be0df5e1384989f1be835043c084 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <[email protected]>
Date: Fri, 31 Jan 2020 05:02:00 -0500
Subject: [PATCH] KVM: s390: do not clobber registers during guest reset/store status

The initial CPU reset clobbers the userspace fpc and the store status ioctl clobbers the guest acrs + fpr. As these calls are only done via ioctl (and not via vcpu_run), no CPU context is loaded, so we can (and must) act directly on the sync regs, not on the thread context.

Quoted 9 lines
Cc [email protected]
Fixes e1788bb995be ("KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load")
Fixes 31d8b8d41a7e ("KVM: s390: handle access registers in the run ioctl not in vcpu_put/load")
Signed-off-by Christian Borntraeger <[email protected]>
Reviewed-by David Hildenbrand <[email protected]>
Reviewed-by Cornelia Huck <[email protected]>
Signed-off-by Janosch Frank <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Christian Borntraeger <[email protected]>

This was a context conflict because we don't have b9224cd7381a ("KVM:
s390: introduce defines for control registers") on 4.14. I've fixed it and queued it up on 4.14.

Signature · 2 lines
Thanks,
Sasha