KVM: s390: enable Transactional Execution

This patch enables transactional execution for KVM guests
on s390 systems zec12 or later.

We rework the allocation of the page containing the sie_block
to also back the Interception Transaction Diagnostic Block.
If available the TE facilities will be enabled.

Setting bit 73 and 50 in vfacilities bitmask reveals the HW
facilities Transactional Memory and Constraint Transactional
Memory respectively to the KVM guest.

Furthermore, the patch restores the Program-Interruption TDB
from the Interception TDB in case a program interception has
occurred and the ITDB has a valid format.
Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/include/asm/kvm_host.h

@@ -106,9 +106,22 @@ struct kvm_s390_sie_block {
 	__u64	gbea;			/* 0x0180 */
 	__u8	reserved188[24];	/* 0x0188 */
 	__u32	fac;			/* 0x01a0 */
-	__u8	reserved1a4[92];	/* 0x01a4 */
+	__u8	reserved1a4[68];	/* 0x01a4 */
+	__u64	itdba;			/* 0x01e8 */
+	__u8	reserved1f0[16];	/* 0x01f0 */
 } __attribute__((packed));
 
+struct kvm_s390_itdb {
+	__u8	data[256];
+} __packed;
+
+struct sie_page {
+	struct kvm_s390_sie_block sie_block;
+	__u8 reserved200[1024];		/* 0x0200 */
+	struct kvm_s390_itdb itdb;	/* 0x0600 */
+	__u8 reserved700[2304];		/* 0x0700 */
+} __packed;
+
 struct kvm_vcpu_stat {
 	u32 exit_userspace;
 	u32 exit_null;

arch/s390/kvm/intercept.c

@@ -112,6 +112,17 @@ static int handle_instruction(struct kvm_vcpu *vcpu)
 static int handle_prog(struct kvm_vcpu *vcpu)
 {
 	vcpu->stat.exit_program_interruption++;
+
+	/* Restore ITDB to Program-Interruption TDB in guest memory */
+	if (IS_TE_ENABLED(vcpu) &&
+	    !(current->thread.per_flags & PER_FLAG_NO_TE) &&
+	    IS_ITDB_VALID(vcpu)) {
+		copy_to_guest(vcpu, TDB_ADDR, vcpu->arch.sie_block->itdba,
+			      sizeof(struct kvm_s390_itdb));
+		memset((void *) vcpu->arch.sie_block->itdba, 0,
+		       sizeof(struct kvm_s390_itdb));
+	}
+
 	trace_kvm_s390_intercept_prog(vcpu, vcpu->arch.sie_block->iprcc);
 	return kvm_s390_inject_program_int(vcpu, vcpu->arch.sie_block->iprcc);
 }

arch/s390/kvm/kvm-s390.c

@@ -395,6 +395,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 						    CPUSTAT_STOPPED |
 						    CPUSTAT_GED);
 	vcpu->arch.sie_block->ecb   = 6;
+	if (test_vfacility(50) && test_vfacility(73))
+		vcpu->arch.sie_block->ecb |= 0x10;
+
 	vcpu->arch.sie_block->ecb2  = 8;
 	vcpu->arch.sie_block->eca   = 0xC1002001U;
 	vcpu->arch.sie_block->fac   = (int) (long) vfacilities;
@@ -411,6 +414,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
 				      unsigned int id)
 {
 	struct kvm_vcpu *vcpu;
+	struct sie_page *sie_page;
 	int rc = -EINVAL;
 
 	if (id >= KVM_MAX_VCPUS)
@@ -422,12 +426,13 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
 	if (!vcpu)
 		goto out;
 
-	vcpu->arch.sie_block = (struct kvm_s390_sie_block *)
-					get_zeroed_page(GFP_KERNEL);
-
-	if (!vcpu->arch.sie_block)
+	sie_page = (struct sie_page *) get_zeroed_page(GFP_KERNEL);
+	if (!sie_page)
 		goto out_free_cpu;
 
+	vcpu->arch.sie_block = &sie_page->sie_block;
+	vcpu->arch.sie_block->itdba = (unsigned long) &sie_page->itdb;
+
 	vcpu->arch.sie_block->icpua = id;
 	if (!kvm_is_ucontrol(kvm)) {
 		if (!kvm->arch.sca) {
@@ -1178,8 +1183,8 @@ static int __init kvm_s390_init(void)
 		return -ENOMEM;
 	}
 	memcpy(vfacilities, S390_lowcore.stfle_fac_list, 16);
-	vfacilities[0] &= 0xff82fff3f47c0000UL;
-	vfacilities[1] &= 0x001c000000000000UL;
+	vfacilities[0] &= 0xff82fff3f47c2000UL;
+	vfacilities[1] &= 0x005c000000000000UL;
 	return 0;
 }
 

arch/s390/kvm/kvm-s390.h

@@ -26,6 +26,12 @@ extern unsigned long *vfacilities;
 
 int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu);
 
+/* Transactional Memory Execution related macros */
+#define IS_TE_ENABLED(vcpu)	((vcpu->arch.sie_block->ecb & 0x10))
+#define TDB_ADDR		0x1800UL
+#define TDB_FORMAT1		1
+#define IS_ITDB_VALID(vcpu)	((*(char *)vcpu->arch.sie_block->itdba == TDB_FORMAT1))
+
 #define VM_EVENT(d_kvm, d_loglevel, d_string, d_args...)\
 do { \
 	debug_sprintf_event(d_kvm->arch.dbf, d_loglevel, d_string "\n", \