[SRU][R][PATCH 4/5] KVM: s390: vsie: Accommodate ESA prefix pages

[Massimiliano Pellizzer]

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

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

The prefix page address occupies a different number
of bits for z/Architecture versus ESA mode. Adjust the
definition to cover both, and permit an ESA mode
address within the nested codepath.

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 c0dcada088ffb5bbac3fc17a416ed2c225f49b9c)
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 arch/s390/include/asm/kvm_host_types.h | 3 +--
 arch/s390/kvm/kvm-s390.h               | 5 ++++-
 arch/s390/kvm/vsie.c                   | 7 ++++++-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h
index 1394d3fb648f..3f50942bdfe6 100644
--- a/arch/s390/include/asm/kvm_host_types.h
+++ b/arch/s390/include/asm/kvm_host_types.h
@@ -137,8 +137,7 @@ struct mcck_volatile_info {
 struct kvm_s390_sie_block {
 	atomic_t cpuflags;		/* 0x0000 */
 	__u32 : 1;			/* 0x0004 */
-	__u32 prefix : 18;
-	__u32 : 1;
+	__u32 prefix : 19;
 	__u32 ibc : 12;
 	__u8	reserved08[4];		/* 0x0008 */
 #define PROG_IN_SIE (1<<0)
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index bf1d7798c1af..dc0573b7aa4b 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -122,7 +122,9 @@ static inline int kvm_is_ucontrol(struct kvm *kvm)
 #endif
 }
 
-#define GUEST_PREFIX_SHIFT 13
+#define GUEST_PREFIX_SHIFT 12
+#define GUEST_PREFIX_MASK_ZARCH 0x7fffe
+#define GUEST_PREFIX_MASK_ESA   0x7ffff
 static inline u32 kvm_s390_get_prefix(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.sie_block->prefix << GUEST_PREFIX_SHIFT;
@@ -133,6 +135,7 @@ static inline void kvm_s390_set_prefix(struct kvm_vcpu *vcpu, u32 prefix)
 	VCPU_EVENT(vcpu, 3, "set prefix of cpu %03u to 0x%x", vcpu->vcpu_id,
 		   prefix);
 	vcpu->arch.sie_block->prefix = prefix >> GUEST_PREFIX_SHIFT;
+	vcpu->arch.sie_block->prefix &= GUEST_PREFIX_MASK_ZARCH;
 	kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 	kvm_make_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu);
 }
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index a3cf1d89d573..e5a23f1c9749 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -479,7 +479,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
 	/* READ_ONCE does not work on bitfields - use a temporary variable */
 	const uint32_t __new_prefix = scb_o->prefix;
-	const uint32_t new_prefix = READ_ONCE(__new_prefix);
+	uint32_t new_prefix = READ_ONCE(__new_prefix);
 	const bool wants_tx = READ_ONCE(scb_o->ecb) & ECB_TE;
 	bool had_tx = scb_s->ecb & ECB_TE;
 	unsigned long new_mso = 0;
@@ -527,6 +527,11 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 
 	scb_s->icpua = scb_o->icpua;
 
+	if (!(atomic_read(&scb_s->cpuflags) & CPUSTAT_ZARCH))
+		new_prefix &= GUEST_PREFIX_MASK_ESA;
+	else
+		new_prefix &= GUEST_PREFIX_MASK_ZARCH;
+
 	if (!(atomic_read(&scb_s->cpuflags) & CPUSTAT_SM))
 		new_mso = READ_ONCE(scb_o->mso) & 0xfffffffffff00000UL;
 	/* if the hva of the prefix changes, we have to remap the prefix */
-- 
2.53.0