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KVM: s390: vsie: support STFLE interpretation

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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 <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
David Hildenbrand 2015-11-26 14:11:19 +01:00 committed by Christian Borntraeger
parent 4ceafa9027
commit 66b630d5b7
1 changed files with 47 additions and 2 deletions
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49
arch/s390/kvm/vsie.c
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@ -18,6 +18,7 @@
#include <asm/mmu_context.h>
#include <asm/sclp.h>
#include <asm/nmi.h>
#include <asm/dis.h>
#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);