KVM: s390: vsie: initial support for nested virtualization

This patch adds basic support for nested virtualization on s390x, called
VSIE (virtual SIE) and allows it to be used by the guest if the necessary
facilities are supported by the hardware and enabled for the guest.

In order to make this work, we have to shadow the sie control block
provided by guest 2. In order to gain some performance, we have to
reuse the same shadow blocks as good as possible. For now, we allow
as many shadow blocks as we have VCPUs (that way, every VCPU can run the
VSIE concurrently).

We have to watch out for the prefix getting unmapped out of our shadow
gmap and properly get the VCPU out of VSIE in that case, to fault the
prefix pages back in. We use the PROG_REQUEST bit for that purpose.

This patch is based on an initial prototype by Tobias Elpelt.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 96bef30e2e33..255609c86901 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -145,7 +145,7 @@ struct kvm_s390_sie_block {
 	__u64	cputm;			/* 0x0028 */
 	__u64	ckc;			/* 0x0030 */
 	__u64	epoch;			/* 0x0038 */
-	__u8	reserved40[4];		/* 0x0040 */
+	__u32	svcc;			/* 0x0040 */
 #define LCTL_CR0	0x8000
 #define LCTL_CR6	0x0200
 #define LCTL_CR9	0x0040
@@ -167,6 +167,9 @@ struct kvm_s390_sie_block {
 #define ICPT_INST	0x04
 #define ICPT_PROGI	0x08
 #define ICPT_INSTPROGI	0x0C
+#define ICPT_EXTINT	0x14
+#define ICPT_VALIDITY	0x20
+#define ICPT_STOP	0x28
 #define ICPT_OPEREXC	0x2C
 #define ICPT_PARTEXEC	0x38
 #define ICPT_IOINST	0x40
@@ -281,6 +284,7 @@ struct kvm_vcpu_stat {
 	u32 instruction_stsi;
 	u32 instruction_stfl;
 	u32 instruction_tprot;
+	u32 instruction_sie;
 	u32 instruction_essa;
 	u32 instruction_sthyi;
 	u32 instruction_sigp_sense;
@@ -637,6 +641,14 @@ struct sie_page2 {
 	u8 reserved900[0x1000 - 0x900];			/* 0x0900 */
 } __packed;
 
+struct kvm_s390_vsie {
+	struct mutex mutex;
+	struct radix_tree_root addr_to_page;
+	int page_count;
+	int next;
+	struct page *pages[KVM_MAX_VCPUS];
+};
+
 struct kvm_arch{
 	void *sca;
 	int use_esca;
@@ -661,6 +673,7 @@ struct kvm_arch{
 	struct sie_page2 *sie_page2;
 	struct kvm_s390_cpu_model model;
 	struct kvm_s390_crypto crypto;
+	struct kvm_s390_vsie vsie;
 	u64 epoch;
 	/* subset of available cpu features enabled by user space */
 	DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS);