From 66b630d5b7f2d3afb5e8eddad3e8326091375f1a Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 26 Nov 2015 14:11:19 +0100 Subject: [PATCH] KVM: s390: vsie: support STFLE interpretation Issuing STFLE is extremely rare. Instead of copying 2k on every VSIE call, let's do this lazily, when a guest 3 tries to execute STFLE. We can setup the block and retry. Unfortunately, we can't directly forward that facility list, as we only have a 31 bit address for the facility list designation. So let's use a DMA allocation for our vsie_page instead for now. Acked-by: Christian Borntraeger Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- arch/s390/kvm/vsie.c | 49 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 47 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index aaed63ce29b2..cd4bbfa72881 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "kvm-s390.h" #include "gaccess.h" @@ -27,7 +28,8 @@ struct vsie_page { struct kvm_s390_sie_block *scb_o; /* 0x0200 */ /* the shadow gmap in use by the vsie_page */ struct gmap *gmap; /* 0x0208 */ - __u8 reserved[0x1000 - 0x0210]; /* 0x0210 */ + __u8 reserved[0x0800 - 0x0210]; /* 0x0210 */ + __u8 fac[S390_ARCH_FAC_LIST_SIZE_BYTE]; /* 0x0800 */ } __packed; /* trigger a validity icpt for the given scb */ @@ -194,6 +196,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) scb_s->ecb2 = 0; scb_s->ecb3 = 0; scb_s->ecd = 0; + scb_s->fac = 0; rc = prepare_cpuflags(vcpu, vsie_page); if (rc) @@ -521,6 +524,44 @@ static inline void clear_vsie_icpt(struct vsie_page *vsie_page) vsie_page->scb_s.icptcode = 0; } +/* rewind the psw and clear the vsie icpt, so we can retry execution */ +static void retry_vsie_icpt(struct vsie_page *vsie_page) +{ + struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s; + int ilen = insn_length(scb_s->ipa >> 8); + + /* take care of EXECUTE instructions */ + if (scb_s->icptstatus & 1) { + ilen = (scb_s->icptstatus >> 4) & 0x6; + if (!ilen) + ilen = 4; + } + scb_s->gpsw.addr = __rewind_psw(scb_s->gpsw, ilen); + clear_vsie_icpt(vsie_page); +} + +/* + * Try to shadow + enable the guest 2 provided facility list. + * Retry instruction execution if enabled for and provided by guest 2. + * + * Returns: - 0 if handled (retry or guest 2 icpt) + * - > 0 if control has to be given to guest 2 + */ +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 = vsie_page->scb_o->fac & 0x7ffffff8U; + + if (fac && test_kvm_facility(vcpu->kvm, 7)) { + retry_vsie_icpt(vsie_page); + if (read_guest_real(vcpu, fac, &vsie_page->fac, + sizeof(vsie_page->fac))) + return set_validity_icpt(scb_s, 0x1090U); + scb_s->fac = (__u32)(__u64) &vsie_page->fac; + } + return 0; +} + /* * Run the vsie on a shadow scb and a shadow gmap, without any further * sanity checks, handling SIE faults. @@ -558,6 +599,10 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) return handle_fault(vcpu, vsie_page); switch (scb_s->icptcode) { + case ICPT_INST: + if (scb_s->ipa == 0xb2b0) + rc = handle_stfle(vcpu, vsie_page); + break; case ICPT_STOP: /* stop not requested by g2 - must have been a kick */ if (!(atomic_read(&scb_o->cpuflags) & CPUSTAT_STOP_INT)) @@ -690,7 +735,7 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) mutex_lock(&kvm->arch.vsie.mutex); if (kvm->arch.vsie.page_count < nr_vcpus) { - page = alloc_page(GFP_KERNEL | __GFP_ZERO); + page = alloc_page(GFP_KERNEL | __GFP_ZERO | GFP_DMA); if (!page) { mutex_unlock(&kvm->arch.vsie.mutex); return ERR_PTR(-ENOMEM); -- 2.20.1