Commit 7eef87dc authored Oct 18, 2011 by Carsten Otte Committed by Avi Kivity Oct 30, 2011

KVM: s390: fix register setting



KVM common code does vcpu_load prior to calling our arch ioctls and
vcpu_put after we're done here. Via the kvm_arch_vcpu_load/put
callbacks we do load the fpu and access register state into the
processor, which saves us moving the state on every SIE exit the
kernel handles. However this breaks register setting from userspace,
because of the following sequence:
1a. vcpu load stores userspace register content
1b. vcpu load loads guest register content
2.  kvm_arch_vcpu_ioctl_set_fpu/sregs updates saved guest register content
3a. vcpu put stores the guest registers and overwrites the new content
3b. vcpu put loads the userspace register set again

This patch loads the new guest register state into the cpu, so that the correct
(new) set of guest registers will be stored in step 3a.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent b290411a

arch/s390/kvm/kvm-s390.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -394,6 +394,7 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
		{
		memcpy(&vcpu->arch.guest_acrs, &sregs->acrs, sizeof(sregs->acrs));
		memcpy(&vcpu->arch.sie_block->gcr, &sregs->crs, sizeof(sregs->crs));
		restore_access_regs(vcpu->arch.guest_acrs);
		return 0;
		}

		@@ -409,6 +410,7 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu vcpu, struct kvm_fpu fpu)
		{
		memcpy(&vcpu->arch.guest_fpregs.fprs, &fpu->fprs, sizeof(fpu->fprs));
		vcpu->arch.guest_fpregs.fpc = fpu->fpc;
		restore_fp_regs(&vcpu->arch.guest_fpregs);
		return 0;
		}

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