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Commit 8f2abe6a authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Avi Kivity
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KVM: s390: sie intercept handling 



This path introduces handling of sie intercepts in three flavors: Intercepts
are either handled completely in-kernel by kvm_handle_sie_intercept(),
or passed to userspace with corresponding data in struct kvm_run in case
kvm_handle_sie_intercept() returns -ENOTSUPP.
In case of partial execution in kernel with the need of userspace support,
kvm_handle_sie_intercept() may choose to set up struct kvm_run and return
-EREMOTE.

The trivial intercept reasons are handled in this patch:
handle_noop() just does nothing for intercepts that don't require our support
  at all
handle_stop() is called when a cpu enters stopped state, and it drops out to
  userland after updating our vcpu state
handle_validity() faults in the cpu lowcore if needed, or passes the request
  to userland

Acked-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarCarsten Otte <cotte@de.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent b0c632db

arch/s390/kvm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -10,5 +10,5 @@ common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o) 


EXTRA_CFLAGS += -Ivirt/kvm -Iarch/s390/kvm



kvm-objs := $(common-objs) kvm-s390.o sie64a.o

kvm-objs := $(common-objs) kvm-s390.o sie64a.o intercept.o

obj-$(CONFIG_KVM) += kvm.o

arch/s390/kvm/intercept.c

0 → 100644
+80 −0
Original line number Diff line number Diff line 
/*

 * intercept.c - in-kernel handling for sie intercepts

 *

 * Copyright IBM Corp. 2008

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License (version 2 only)

 * as published by the Free Software Foundation.

 *

 *    Author(s): Carsten Otte <cotte@de.ibm.com>

 *               Christian Borntraeger <borntraeger@de.ibm.com>

 */



#include <linux/kvm_host.h>

#include <linux/errno.h>

#include <linux/pagemap.h>



#include <asm/kvm_host.h>



#include "kvm-s390.h"



static int handle_noop(struct kvm_vcpu *vcpu)

{

	switch (vcpu->arch.sie_block->icptcode) {

	case 0x10:

		vcpu->stat.exit_external_request++;

		break;

	case 0x14:

		vcpu->stat.exit_external_interrupt++;

		break;

	default:

		break; /* nothing */

	}

	return 0;

}



static int handle_stop(struct kvm_vcpu *vcpu)

{

	vcpu->stat.exit_stop_request++;

	VCPU_EVENT(vcpu, 3, "%s", "cpu stopped");

	atomic_clear_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags);

	return -ENOTSUPP;

}



static int handle_validity(struct kvm_vcpu *vcpu)

{

	int viwhy = vcpu->arch.sie_block->ipb >> 16;

	vcpu->stat.exit_validity++;

	if (viwhy == 0x37) {

		fault_in_pages_writeable((char __user *)

					 vcpu->kvm->arch.guest_origin +

					 vcpu->arch.sie_block->prefix,

					 PAGE_SIZE);

		return 0;

	}

	VCPU_EVENT(vcpu, 2, "unhandled validity intercept code %d",

		   viwhy);

	return -ENOTSUPP;

}



static const intercept_handler_t intercept_funcs[0x48 >> 2] = {

	[0x00 >> 2] = handle_noop,

	[0x10 >> 2] = handle_noop,

	[0x14 >> 2] = handle_noop,

	[0x20 >> 2] = handle_validity,

	[0x28 >> 2] = handle_stop,

};



int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)

{

	intercept_handler_t func;

	u8 code = vcpu->arch.sie_block->icptcode;



	if (code & 3 || code > 0x48)

		return -ENOTSUPP;

	func = intercept_funcs[code >> 2];

	if (func)

		return func(vcpu);

	return -ENOTSUPP;

}

arch/s390/kvm/kvm-s390.c

+45 −1
Original line number Diff line number Diff line
@@ -23,12 +23,17 @@ 
#include <asm/lowcore.h>

#include <asm/pgtable.h>



#include "kvm-s390.h"

#include "gaccess.h"



#define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU



struct kvm_stats_debugfs_item debugfs_entries[] = {

	{ "userspace_handled", VCPU_STAT(exit_userspace) },

	{ "exit_validity", VCPU_STAT(exit_validity) },

	{ "exit_stop_request", VCPU_STAT(exit_stop_request) },

	{ "exit_external_request", VCPU_STAT(exit_external_request) },

	{ "exit_external_interrupt", VCPU_STAT(exit_external_interrupt) },

	{ NULL }

};
@@ -380,6 +385,7 @@ static void __vcpu_run(struct kvm_vcpu *vcpu) 


int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)

{

	int rc;

	sigset_t sigsaved;



	vcpu_load(vcpu);
@@ -389,8 +395,46 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 


	atomic_set_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags);



	switch (kvm_run->exit_reason) {

	case KVM_EXIT_S390_SIEIC:

		vcpu->arch.sie_block->gpsw.mask = kvm_run->s390_sieic.mask;

		vcpu->arch.sie_block->gpsw.addr = kvm_run->s390_sieic.addr;

		break;

	case KVM_EXIT_UNKNOWN:

	case KVM_EXIT_S390_RESET:

		break;

	default:

		BUG();

	}



	might_sleep();



	do {

		__vcpu_run(vcpu);



		rc = kvm_handle_sie_intercept(vcpu);

	} while (!signal_pending(current) && !rc);



	if (signal_pending(current) && !rc)

		rc = -EINTR;



	if (rc == -ENOTSUPP) {

		/* intercept cannot be handled in-kernel, prepare kvm-run */

		kvm_run->exit_reason         = KVM_EXIT_S390_SIEIC;

		kvm_run->s390_sieic.icptcode = vcpu->arch.sie_block->icptcode;

		kvm_run->s390_sieic.mask     = vcpu->arch.sie_block->gpsw.mask;

		kvm_run->s390_sieic.addr     = vcpu->arch.sie_block->gpsw.addr;

		kvm_run->s390_sieic.ipa      = vcpu->arch.sie_block->ipa;

		kvm_run->s390_sieic.ipb      = vcpu->arch.sie_block->ipb;

		rc = 0;

	}



	if (rc == -EREMOTE) {

		/* intercept was handled, but userspace support is needed

		 * kvm_run has been prepared by the handler */

		rc = 0;

	}



	if (vcpu->sigset_active)

		sigprocmask(SIG_SETMASK, &sigsaved, NULL);

arch/s390/kvm/kvm-s390.h

+7 −0
Original line number Diff line number Diff line
@@ -13,6 +13,13 @@ 


#ifndef ARCH_S390_KVM_S390_H

#define ARCH_S390_KVM_S390_H



#include <linux/kvm_host.h>



typedef int (*intercept_handler_t)(struct kvm_vcpu *vcpu);



int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu);



#define VM_EVENT(d_kvm, d_loglevel, d_string, d_args...)\

do { \

	debug_sprintf_event(d_kvm->arch.dbf, d_loglevel, d_string "\n", \

include/asm-s390/kvm_host.h

+4 −0
Original line number Diff line number Diff line
@@ -101,6 +101,10 @@ struct sie_block { 


struct kvm_vcpu_stat {

	u32 exit_userspace;

	u32 exit_external_request;

	u32 exit_external_interrupt;

	u32 exit_stop_request;

	u32 exit_validity;

};



struct kvm_vcpu_arch {