[PATCH v2 3/4] KVM: s390: vsie: Refactor handle_stfle

[Christoph Schlameuss]

From: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>

Use switch case in anticipation of handling format-1 and format-2
facility list designations in the future.
As the alternate STFLE facilities are not enabled, only case 0 is
possible.
No functional change intended.

Signed-off-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
Co-developed-by: Christoph Schlameuss <schlameuss@xxxxxxxxxxxxx>
Signed-off-by: Christoph Schlameuss <schlameuss@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_host.h |  2 ++
 arch/s390/include/uapi/asm/kvm.h |  1 +
 arch/s390/kvm/vsie.c             | 53 ++++++++++++++++++++++++++++------------
 3 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 64a50f0862aabb994089090c750bd312a7233e2c..23d17700319a5ef2031eabcad34b6191d1ef9b21 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -484,6 +484,8 @@ struct s390_io_adapter {
 #define MAX_S390_IO_ADAPTERS ((MAX_ISC + 1) * 8)
 #define MAX_S390_ADAPTER_MAPS 256
 
+#define S390_ARCH_FAC_ORIGIN_MASK 0x7ffffff8U
+
 /* maximum size of facilities and facility mask is 2k bytes */
 #define S390_ARCH_FAC_LIST_SIZE_BYTE (1<<11)
 #define S390_ARCH_FAC_LIST_SIZE_U64 \
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 60345dd2cba2d611b76f8b5c70eab8f0abab4b9b..4192769b5ce069ba28d00d7cf1c4f1b34037d633 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -444,6 +444,7 @@ struct kvm_s390_vm_cpu_machine {
 #define KVM_S390_VM_CPU_FEAT_PFMFI	11
 #define KVM_S390_VM_CPU_FEAT_SIGPIF	12
 #define KVM_S390_VM_CPU_FEAT_KSS	13
+#define KVM_S390_VM_CPU_FEAT_ASTFLEIE2	14
 struct kvm_s390_vm_cpu_feat {
 	__u64 feat[16];
 };
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index d249b10044eb7595295fc20e9287e0629958d896..3a2c644ef4fc630e2a13475fc1600c8053520bcd 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -6,12 +6,15 @@
  *
  *    Author(s): David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
  */
+#include <linux/align.h>
 #include <linux/vmalloc.h>
 #include <linux/kvm_host.h>
 #include <linux/bug.h>
+#include <linux/compiler.h>
 #include <linux/list.h>
 #include <linux/bitmap.h>
 #include <linux/sched/signal.h>
+#include <linux/stddef.h>
 #include <linux/io.h>
 #include <linux/mman.h>
 
@@ -979,6 +982,23 @@ static void retry_vsie_icpt(struct vsie_page *vsie_page)
 	clear_vsie_icpt(vsie_page);
 }
 
+static int handle_stfle_0(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page,
+			  u32 fac_list_origin)
+{
+	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
+
+	/*
+	 * format-0 -> size of nested guest's facility list == guest's size
+	 * guest's size == host's size, since STFLE is interpretatively executed
+	 * using a format-0 for the guest, too.
+	 */
+	if (read_guest_real(vcpu, fac_list_origin, &vsie_page->fac,
+			    stfle_size() * sizeof(u64)))
+		return set_validity_icpt(scb_s, 0x1090U);
+	scb_s->fac = (u32)virt_to_phys(&vsie_page->fac);
+	return 0;
+}
+
 /*
  * Try to shadow + enable the guest 2 provided facility list.
  * Retry instruction execution if enabled for and provided by guest 2.
@@ -988,29 +1008,30 @@ static void retry_vsie_icpt(struct vsie_page *vsie_page)
  */
 static int handle_stfle(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 {
-	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
-	__u32 fac = READ_ONCE(vsie_page->scb_o->fac);
+	bool has_astfleie2 = test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_ASTFLEIE2);
+	u32 fac = READ_ONCE(vsie_page->scb_o->fac);
+	int format_mask, format;
+	u32 origin;
+
+	BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct vsie_page, fac), 8));
 
-	/*
-	 * Alternate-STFLE-Interpretive-Execution facilities are not supported
-	 * -> format-0 flcb
-	 */
 	if (fac && test_kvm_facility(vcpu->kvm, 7)) {
 		retry_vsie_icpt(vsie_page);
 		/*
 		 * The facility list origin (FLO) is in bits 1 - 28 of the FLD
 		 * so we need to mask here before reading.
 		 */
-		fac = fac & 0x7ffffff8U;
-		/*
-		 * format-0 -> size of nested guest's facility list == guest's size
-		 * guest's size == host's size, since STFLE is interpretatively executed
-		 * using a format-0 for the guest, too.
-		 */
-		if (read_guest_real(vcpu, fac, &vsie_page->fac,
-				    stfle_size() * sizeof(u64)))
-			return set_validity_icpt(scb_s, 0x1090U);
-		scb_s->fac = (u32)virt_to_phys(&vsie_page->fac);
+		origin = fac & S390_ARCH_FAC_ORIGIN_MASK;
+		format_mask = has_astfleie2 ? 3 : 0;
+		format = fac & format_mask;
+		switch (format) {
+		case 0:
+			return handle_stfle_0(vcpu, vsie_page, origin);
+		case 1:
+		case 2:
+		case 3:
+			unreachable();
+		}
 	}
 	return 0;
 }

-- 
2.53.0