Merge tag 'kvm-s390-next-6.8-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

- uvdevice fixed additional data return length
- stfle (feature indication) vsie fixes and minor cleanup

5 files changed, 46 insertions, 4 deletions

diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h
index 94b6919026dfb..796007125dff2 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -111,4 +111,10 @@ static inline void stfle(u64 *stfle_fac_list, int size)
 	preempt_enable();
 }
 
+/**
+ * stfle_size - Actual size of the facility list as specified by stfle
+ * (number of double words)
+ */
+unsigned int stfle_size(void);
+
 #endif /* __ASM_FACILITY_H */
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 67a298b6cf6e9..52664105a473f 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -818,7 +818,7 @@ struct s390_io_adapter {
 
 struct kvm_s390_cpu_model {
 	/* facility mask supported by kvm & hosting machine */
-	__u64 fac_mask[S390_ARCH_FAC_LIST_SIZE_U64];
+	__u64 fac_mask[S390_ARCH_FAC_MASK_SIZE_U64];
 	struct kvm_s390_vm_cpu_subfunc subfuncs;
 	/* facility list requested by guest (in dma page) */
 	__u64 *fac_list;
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 353def93973b3..7a562b4199c81 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -41,7 +41,7 @@ obj-y	+= sysinfo.o lgr.o os_info.o ctlreg.o
 obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
 obj-y	+= entry.o reipl.o kdebugfs.o alternative.o
 obj-y	+= nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o
-obj-y	+= smp.o text_amode31.o stacktrace.o abs_lowcore.o
+obj-y	+= smp.o text_amode31.o stacktrace.o abs_lowcore.o facility.o
 
 extra-y				+= vmlinux.lds
 
diff --git a/arch/s390/kernel/facility.c b/arch/s390/kernel/facility.c
new file mode 100644
index 0000000000000..f02127219a27b
--- /dev/null
+++ b/arch/s390/kernel/facility.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright IBM Corp. 2023
+ */
+
+#include <asm/facility.h>
+
+unsigned int stfle_size(void)
+{
+	static unsigned int size;
+	unsigned int r;
+	u64 dummy;
+
+	r = READ_ONCE(size);
+	if (!r) {
+		r = __stfle_asm(&dummy, 1) + 1;
+		WRITE_ONCE(size, r);
+	}
+	return r;
+}
+EXPORT_SYMBOL(stfle_size);
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 8207a892bbe22..fef42e2a80a2a 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -19,6 +19,7 @@
 #include <asm/nmi.h>
 #include <asm/dis.h>
 #include <asm/fpu/api.h>
+#include <asm/facility.h>
 #include "kvm-s390.h"
 #include "gaccess.h"
 
@@ -984,12 +985,26 @@ 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) & 0x7ffffff8U;
+	__u32 fac = READ_ONCE(vsie_page->scb_o->fac);
 
+	/*
+	 * 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,
-				    sizeof(vsie_page->fac)))
+				    stfle_size() * sizeof(u64)))
 			return set_validity_icpt(scb_s, 0x1090U);
 		scb_s->fac = (__u32)(__u64) &vsie_page->fac;
 	}