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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
index 0d8d1135a278f4254dae801a9cb427bbe56579b3..27882b35ef044a6a38271030957e0b0fbd42a189 100644 (file)
--- a/arch/s390/kvm/Makefile
+++ b/arch/s390/kvm/Makefile
@@ -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

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
new file mode 100644 (file)
index 0000000..e757230
--- /dev/null
+++ b/arch/s390/kvm/intercept.c
@@ -0,0 +1,80 @@
+/*
+ * 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;
+}

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6e1e1d39ae158e6c66ba5eed1e7162bf0042293b..a906499214bb2ff471ef23d6cfd0ad40041815b7 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -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);
@@ -389,7 +395,45 @@ 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);
 
-       __vcpu_run(vcpu);
+       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);

diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index ed64a22ca86f427eb9061ba7e0b827d5423abf5f..5b82527b7f863bb2884b2b886395426bddd5a43f 100644 (file)
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -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", \

diff --git a/include/asm-s390/kvm_host.h b/include/asm-s390/kvm_host.h
index c9d653333106579541ea376a35a2ddc567086ae6..8965b38d0a3251dfb3122a1c93bdb715fb4cabaf 100644 (file)
--- a/include/asm-s390/kvm_host.h
+++ b/include/asm-s390/kvm_host.h
@@ -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 {

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 2367ff0c5dd085188c16292d1e3f5a222cbdd1da..f2acd6b9ab4d55d4732b3518b6b7e9c7441585e6 100644 (file)
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -74,6 +74,7 @@ struct kvm_irqchip {
 #define KVM_EXIT_INTR             10
 #define KVM_EXIT_SET_TPR          11
 #define KVM_EXIT_TPR_ACCESS       12
+#define KVM_EXIT_S390_SIEIC       13
 
 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
@@ -138,6 +139,14 @@ struct kvm_run {
                        __u32 is_write;
                        __u32 pad;
                } tpr_access;
+               /* KVM_EXIT_S390_SIEIC */
+               struct {
+                       __u8 icptcode;
+                       __u64 mask; /* psw upper half */
+                       __u64 addr; /* psw lower half */
+                       __u16 ipa;
+                       __u32 ipb;
+               } s390_sieic;
                /* Fix the size of the union. */
                char padding[256];
        };