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Commit 66b630d5 authored by David Hildenbrand's avatar David Hildenbrand Committed by Christian Borntraeger
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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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 4ceafa90

arch/s390/kvm/vsie.c

+47 −2
Original line number Diff line number Diff line
@@ -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);