Patch "KVM: s390: Fix skey emulation permission check" has been added to the 4.9-stable tree

Patch "KVM: s390: Fix skey emulation permission check" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KVM: s390: Fix skey emulation permission check

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-s390-fix-skey-emulation-permission-check.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ca76ec9ca871e67d8cd0b6caba24aca3d3ac4546 Mon Sep 17 00:00:00 2001
From: Janosch Frank <frankja@linux.vnet.ibm.com>
Date: Mon, 4 Dec 2017 12:19:11 +0100
Subject: KVM: s390: Fix skey emulation permission check

From: Janosch Frank <frankja@linux.vnet.ibm.com>

commit ca76ec9ca871e67d8cd0b6caba24aca3d3ac4546 upstream.

All skey functions call skey_check_enable at their start, which checks
if we are in the PSTATE and injects a privileged operation exception
if we are.

Unfortunately they continue processing afterwards and perform the
operation anyhow as skey_check_enable does not deliver an error if the
exception injection was successful.

Let's move the PSTATE check into the skey functions and exit them on
such an occasion, also we now do not enable skey handling anymore in
such a case.

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: a7e19ab ("KVM: s390: handle missing storage-key facility")
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/s390/kvm/priv.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -197,8 +197,6 @@ static int try_handle_skey(struct kvm_vc
 		VCPU_EVENT(vcpu, 4, "%s", "retrying storage key operation");
 		return -EAGAIN;
 	}
-	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
-		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
 	return 0;
 }
 
@@ -209,6 +207,9 @@ static int handle_iske(struct kvm_vcpu *
 	int reg1, reg2;
 	int rc;
 
+	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
+		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
+
 	rc = try_handle_skey(vcpu);
 	if (rc)
 		return rc != -EAGAIN ? rc : 0;
@@ -238,6 +239,9 @@ static int handle_rrbe(struct kvm_vcpu *
 	int reg1, reg2;
 	int rc;
 
+	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
+		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
+
 	rc = try_handle_skey(vcpu);
 	if (rc)
 		return rc != -EAGAIN ? rc : 0;
@@ -273,6 +277,9 @@ static int handle_sske(struct kvm_vcpu *
 	int reg1, reg2;
 	int rc;
 
+	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
+		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
+
 	rc = try_handle_skey(vcpu);
 	if (rc)
 		return rc != -EAGAIN ? rc : 0;


Patches currently in stable-queue which might be from frankja@linux.vnet.ibm.com are

queue-4.9/kvm-s390-fix-skey-emulation-permission-check.patch