[SRU][R][PATCH 3/5] KVM: s390: vsie: Disable some bits when in ESA mode

[Massimiliano Pellizzer]

From: Eric Farman <farman at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/2153159

In the event that a nested guest is put in ESA mode,
ensure that some bits are scrubbed from the shadow SCB.

Reviewed-by: Christian Borntraeger <borntraeger at linux.ibm.com>
Signed-off-by: Eric Farman <farman at linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner at linux.ibm.com>
Signed-off-by: Janosch Frank <frankja at linux.ibm.com>
(cherry picked from commit a9640e2eb7110f0aafda8905acbf5b4ae8db07a4)
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 arch/s390/kvm/vsie.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index eee1b72e14df..a3cf1d89d573 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -387,6 +387,17 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	return 0;
 }
 
+static void shadow_esa(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
+{
+	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
+
+	/* Ensure these bits are indeed turned off */
+	scb_s->eca &= ~ECA_VX;
+	scb_s->ecb &= ~(ECB_GS | ECB_TE);
+	scb_s->ecb3 &= ~ECB3_RI;
+	scb_s->ecd &= ~ECD_HOSTREGMGMT;
+}
+
 /* shadow (round up/down) the ibc to avoid validity icpt */
 static void prepare_ibc(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 {
@@ -590,6 +601,9 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	scb_s->hpid = HPID_VSIE;
 	scb_s->cpnc = scb_o->cpnc;
 
+	if (!(atomic_read(&scb_s->cpuflags) & CPUSTAT_ZARCH))
+		shadow_esa(vcpu, vsie_page);
+
 	prepare_ibc(vcpu, vsie_page);
 	rc = shadow_crycb(vcpu, vsie_page);
 out:
-- 
2.53.0