KVM: s390: streamline memslot handling

This patch relocates the variables kvm-s390 uses to track guest mem addr/size.
As discussed dropping the variables at struct kvm_arch level allows to use the
common vcpu->request based mechanism to reload guest memory if e.g. changes
via set_memory_region.

The kick mechanism introduced in this series is used to ensure running vcpus
leave guest state to catch the update.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

5 files changed, 61 insertions, 51 deletions

diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index ed60f3a74a85..03c716a0f01f 100644
--- a/arch/s390/kvm/gaccess.h
+++ b/arch/s390/kvm/gaccess.h
@@ -1,7 +1,7 @@
 /*
  * gaccess.h -  access guest memory
  *
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
  *
  * 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)
@@ -16,13 +16,14 @@
 #include <linux/compiler.h>
 #include <linux/kvm_host.h>
 #include <asm/uaccess.h>
+#include "kvm-s390.h"
 
 static inline void __user *__guestaddr_to_user(struct kvm_vcpu *vcpu,
                                                unsigned long guestaddr)
 {
         unsigned long prefix  = vcpu->arch.sie_block->prefix;
-        unsigned long origin  = vcpu->kvm->arch.guest_origin;
-        unsigned long memsize = vcpu->kvm->arch.guest_memsize;
+        unsigned long origin  = vcpu->arch.sie_block->gmsor;
+        unsigned long memsize = kvm_s390_vcpu_get_memsize(vcpu);
 
         if (guestaddr < 2 * PAGE_SIZE)
                 guestaddr += prefix;
@@ -158,8 +159,8 @@ static inline int copy_to_guest(struct kvm_vcpu *vcpu, unsigned long guestdest,
                                 const void *from, unsigned long n)
 {
         unsigned long prefix  = vcpu->arch.sie_block->prefix;
-        unsigned long origin  = vcpu->kvm->arch.guest_origin;
-        unsigned long memsize = vcpu->kvm->arch.guest_memsize;
+        unsigned long origin  = vcpu->arch.sie_block->gmsor;
+        unsigned long memsize = kvm_s390_vcpu_get_memsize(vcpu);
 
         if ((guestdest < 2 * PAGE_SIZE) && (guestdest + n > 2 * PAGE_SIZE))
                 goto slowpath;
@@ -209,8 +210,8 @@ static inline int copy_from_guest(struct kvm_vcpu *vcpu, void *to,
                                   unsigned long guestsrc, unsigned long n)
 {
         unsigned long prefix  = vcpu->arch.sie_block->prefix;
-        unsigned long origin  = vcpu->kvm->arch.guest_origin;
-        unsigned long memsize = vcpu->kvm->arch.guest_memsize;
+        unsigned long origin  = vcpu->arch.sie_block->gmsor;
+        unsigned long memsize = kvm_s390_vcpu_get_memsize(vcpu);
 
         if ((guestsrc < 2 * PAGE_SIZE) && (guestsrc + n > 2 * PAGE_SIZE))
                 goto slowpath;
@@ -244,8 +245,8 @@ static inline int copy_to_guest_absolute(struct kvm_vcpu *vcpu,
                                          unsigned long guestdest,
                                          const void *from, unsigned long n)
 {
-        unsigned long origin  = vcpu->kvm->arch.guest_origin;
-        unsigned long memsize = vcpu->kvm->arch.guest_memsize;
+        unsigned long origin  = vcpu->arch.sie_block->gmsor;
+        unsigned long memsize = kvm_s390_vcpu_get_memsize(vcpu);
 
         if (guestdest + n > memsize)
                 return -EFAULT;
@@ -262,8 +263,8 @@ static inline int copy_from_guest_absolute(struct kvm_vcpu *vcpu, void *to,
                                            unsigned long guestsrc,
                                            unsigned long n)
 {
-        unsigned long origin  = vcpu->kvm->arch.guest_origin;
-        unsigned long memsize = vcpu->kvm->arch.guest_memsize;
+        unsigned long origin  = vcpu->arch.sie_block->gmsor;
+        unsigned long memsize = kvm_s390_vcpu_get_memsize(vcpu);
 
         if (guestsrc + n > memsize)
                 return -EFAULT;
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 0732ab4305f4..ba9d8a7bc1ac 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -1,7 +1,7 @@
 /*
  * intercept.c - in-kernel handling for sie intercepts
  *
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
  *
  * 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)
@@ -164,9 +164,9 @@ static int handle_validity(struct kvm_vcpu *vcpu)
 
         vcpu->stat.exit_validity++;
         if ((viwhy == 0x37) && (vcpu->arch.sie_block->prefix
-                <= vcpu->kvm->arch.guest_memsize - 2*PAGE_SIZE)){
+                <= kvm_s390_vcpu_get_memsize(vcpu) - 2*PAGE_SIZE)) {
                 rc = fault_in_pages_writeable((char __user *)
-                         vcpu->kvm->arch.guest_origin +
+                         vcpu->arch.sie_block->gmsor +
                          vcpu->arch.sie_block->prefix,
                          2*PAGE_SIZE);
                 if (rc)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 5c1c30259002..098bfa6fbdf6 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1,7 +1,7 @@
 /*
  * s390host.c --  hosting zSeries kernel virtual machines
  *
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
  *
  * 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)
@@ -10,6 +10,7 @@
  *    Author(s): Carsten Otte <cotte@de.ibm.com>
  *               Christian Borntraeger <borntraeger@de.ibm.com>
  *               Heiko Carstens <heiko.carstens@de.ibm.com>
+ *               Christian Ehrhardt <ehrhardt@de.ibm.com>
  */
 
 #include <linux/compiler.h>
@@ -278,16 +279,10 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
         vcpu->arch.sie_block->gbea = 1;
 }
 
-/* The current code can have up to 256 pages for virtio */
-#define VIRTIODESCSPACE (256ul * 4096ul)
-
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 {
         atomic_set(&vcpu->arch.sie_block->cpuflags, CPUSTAT_ZARCH);
-        vcpu->arch.sie_block->gmslm = vcpu->kvm->arch.guest_memsize +
-                                      vcpu->kvm->arch.guest_origin +
-                                      VIRTIODESCSPACE - 1ul;
-        vcpu->arch.sie_block->gmsor = vcpu->kvm->arch.guest_origin;
+        set_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests);
         vcpu->arch.sie_block->ecb   = 2;
         vcpu->arch.sie_block->eca   = 0xC1002001U;
         vcpu->arch.sie_block->fac   = (int) (long) facilities;
@@ -491,9 +486,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         vcpu_load(vcpu);
 
 rerun_vcpu:
+        if (vcpu->requests)
+                if (test_and_clear_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
+                        kvm_s390_vcpu_set_mem(vcpu);
+
         /* verify, that memory has been registered */
-        if (!vcpu->kvm->arch.guest_memsize) {
+        if (!vcpu->arch.sie_block->gmslm) {
                 vcpu_put(vcpu);
+                VCPU_EVENT(vcpu, 3, "%s", "no memory registered to run vcpu");
                 return -EINVAL;
         }
 
@@ -691,7 +691,7 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
            vmas. It is okay to mmap() and munmap() stuff in this slot after
            doing this call at any time */
 
-        if (mem->slot || kvm->arch.guest_memsize)
+        if (mem->slot)
                 return -EINVAL;
 
         if (mem->guest_phys_addr)
@@ -706,36 +706,18 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
         if (!user_alloc)
                 return -EINVAL;
 
-        /* lock all vcpus */
-        for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-                if (!kvm->vcpus[i])
-                        continue;
-                if (!mutex_trylock(&kvm->vcpus[i]->mutex))
-                        goto fail_out;
-        }
-
-        kvm->arch.guest_origin = mem->userspace_addr;
-        kvm->arch.guest_memsize = mem->memory_size;
-
-        /* update sie control blocks, and unlock all vcpus */
+        /* request update of sie control block for all available vcpus */
         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
                 if (kvm->vcpus[i]) {
-                        kvm->vcpus[i]->arch.sie_block->gmsor =
-                                kvm->arch.guest_origin;
-                        kvm->vcpus[i]->arch.sie_block->gmslm =
-                                kvm->arch.guest_memsize +
-                                kvm->arch.guest_origin +
-                                VIRTIODESCSPACE - 1ul;
-                        mutex_unlock(&kvm->vcpus[i]->mutex);
+                        if (test_and_set_bit(KVM_REQ_MMU_RELOAD,
+                                                &kvm->vcpus[i]->requests))
+                                continue;
+                        kvm_s390_inject_sigp_stop(kvm->vcpus[i],
+                                                  ACTION_RELOADVCPU_ON_STOP);
                 }
         }
 
         return 0;
-
-fail_out:
-        for (; i >= 0; i--)
-                mutex_unlock(&kvm->vcpus[i]->mutex);
-        return -EINVAL;
 }
 
 void kvm_arch_flush_shadow(struct kvm *kvm)
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 2072cd4a013e..ec5eee7c25d8 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -1,7 +1,7 @@
 /*
  * kvm_s390.h -  definition for kvm on s390
  *
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
  *
  * 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)
@@ -9,6 +9,7 @@
  *
  *    Author(s): Carsten Otte <cotte@de.ibm.com>
  *               Christian Borntraeger <borntraeger@de.ibm.com>
+ *               Christian Ehrhardt <ehrhardt@de.ibm.com>
  */
 
 #ifndef ARCH_S390_KVM_S390_H
@@ -18,6 +19,9 @@
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 
+/* The current code can have up to 256 pages for virtio */
+#define VIRTIODESCSPACE (256ul * 4096ul)
+
 typedef int (*intercept_handler_t)(struct kvm_vcpu *vcpu);
 
 /* negativ values are error codes, positive values for internal conditions */
@@ -54,6 +58,29 @@ int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
 int kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code);
 int kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action);
 
+static inline int kvm_s390_vcpu_get_memsize(struct kvm_vcpu *vcpu)
+{
+        return vcpu->arch.sie_block->gmslm
+                - vcpu->arch.sie_block->gmsor
+                - VIRTIODESCSPACE + 1ul;
+}
+
+static inline void kvm_s390_vcpu_set_mem(struct kvm_vcpu *vcpu)
+{
+        struct kvm_memory_slot *mem;
+
+        down_read(&vcpu->kvm->slots_lock);
+        mem = &vcpu->kvm->memslots[0];
+
+        vcpu->arch.sie_block->gmsor = mem->userspace_addr;
+        vcpu->arch.sie_block->gmslm =
+                mem->userspace_addr +
+                (mem->npages << PAGE_SHIFT) +
+                VIRTIODESCSPACE - 1ul;
+
+        up_read(&vcpu->kvm->slots_lock);
+}
+
 /* implemented in priv.c */
 int kvm_s390_handle_b2(struct kvm_vcpu *vcpu);
 
diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c
index 21897b0f8a36..40c8c6748cfe 100644
--- a/arch/s390/kvm/sigp.c
+++ b/arch/s390/kvm/sigp.c
@@ -189,9 +189,9 @@ static int __sigp_set_prefix(struct kvm_vcpu *vcpu, u16 cpu_addr, u32 address,
         /* make sure that the new value is valid memory */
         address = address & 0x7fffe000u;
         if ((copy_from_guest(vcpu, &tmp,
-                (u64) (address + vcpu->kvm->arch.guest_origin) , 1)) ||
+                (u64) (address + vcpu->arch.sie_block->gmsor) , 1)) ||
            (copy_from_guest(vcpu, &tmp, (u64) (address +
-                        vcpu->kvm->arch.guest_origin + PAGE_SIZE), 1))) {
+                        vcpu->arch.sie_block->gmsor + PAGE_SIZE), 1))) {
                 *reg |= SIGP_STAT_INVALID_PARAMETER;
                 return 1; /* invalid parameter */
         }