[Qemu-devel] [PATCH 13/18] kvm: Consolidate must-have capability checks

[Jan Kiszka]

From: Jan Kiszka <address@hidden>

Instead of splattering the code with #ifdefs and runtime checks for
capabilities we cannot work without anyway, provide central test
infrastructure for verifying their availability both at build and
runtime.

Signed-off-by: Jan Kiszka <address@hidden>
---
 configure          |   39 ++++++++++++++++++++----------
 kvm-all.c          |   67 +++++++++++++++++++++-------------------------------
 kvm.h              |   10 +++++++
 target-i386/kvm.c  |   39 ++++++------------------------
 target-ppc/kvm.c   |    4 +++
 target-s390x/kvm.c |    4 +++
 6 files changed, 79 insertions(+), 84 deletions(-)

diff --git a/configure b/configure
index 9a02d1f..4673bf0 100755
--- a/configure
+++ b/configure
@@ -1662,18 +1662,31 @@ if test "$kvm" != "no" ; then
 #if !defined(KVM_API_VERSION) || KVM_API_VERSION < 12 || KVM_API_VERSION > 12
 #error Invalid KVM version
 #endif
-#if !defined(KVM_CAP_USER_MEMORY)
-#error Missing KVM capability KVM_CAP_USER_MEMORY
-#endif
-#if !defined(KVM_CAP_SET_TSS_ADDR)
-#error Missing KVM capability KVM_CAP_SET_TSS_ADDR
-#endif
-#if !defined(KVM_CAP_DESTROY_MEMORY_REGION_WORKS)
-#error Missing KVM capability KVM_CAP_DESTROY_MEMORY_REGION_WORKS
-#endif
-#if !defined(KVM_CAP_USER_NMI)
-#error Missing KVM capability KVM_CAP_USER_NMI
+EOF
+    must_have_caps="KVM_CAP_USER_MEMORY \
+                    KVM_CAP_DESTROY_MEMORY_REGION_WORKS \
+                    KVM_CAP_COALESCED_MMIO \
+                    KVM_CAP_SYNC_MMU \
+                   "
+    if test \( "$cpu" = "i386" -o "$cpu" = "x86_64" \) ; then
+      must_have_caps="$caps \
+                      KVM_CAP_SET_TSS_ADDR \
+                      KVM_CAP_EXT_CPUID \
+                      KVM_CAP_CLOCKSOURCE \
+                      KVM_CAP_NOP_IO_DELAY \
+                      KVM_CAP_PV_MMU \
+                      KVM_CAP_MP_STATE \
+                      KVM_CAP_USER_NMI \
+                     "
+    fi
+    for c in $must_have_caps ; do
+      cat >> $TMPC <<EOF
+#if !defined($c)
+#error Missing KVM capability $c
 #endif
+EOF
+    done
+    cat >> $TMPC <<EOF
 int main(void) { return 0; }
 EOF
   if test "$kerneldir" != "" ; then
@@ -1708,8 +1721,8 @@ EOF
        | awk -F "error: " '{if (NR>1) printf(", "); printf("%s",$2);}'`
         if test "$kvmerr" != "" ; then
           echo -e "${kvmerr}\n\
-      NOTE: To enable KVM support, update your kernel to 2.6.29+ or install \
-  recent kvm-kmod from http://sourceforge.net/projects/kvm.";
+NOTE: To enable KVM support, update your kernel to 2.6.29+ or install \
+recent kvm-kmod from http://sourceforge.net/projects/kvm.";
         fi
       fi
       feature_not_found "kvm"
diff --git a/kvm-all.c b/kvm-all.c
index 8053f92..3a1f63b 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -63,9 +63,7 @@ struct KVMState
     int fd;
     int vmfd;
     int coalesced_mmio;
-#ifdef KVM_CAP_COALESCED_MMIO
     struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
-#endif
     int broken_set_mem_region;
     int migration_log;
     int vcpu_events;
@@ -82,6 +80,12 @@ struct KVMState
 
 static KVMState *kvm_state;
 
+static const KVMCapabilityInfo kvm_required_capabilites[] = {
+    KVM_CAP_INFO(USER_MEMORY),
+    KVM_CAP_INFO(DESTROY_MEMORY_REGION_WORKS),
+    KVM_CAP_LAST_INFO
+};
+
 static KVMSlot *kvm_alloc_slot(KVMState *s)
 {
     int i;
@@ -227,12 +231,10 @@ int kvm_init_vcpu(CPUState *env)
         goto err;
     }
 
-#ifdef KVM_CAP_COALESCED_MMIO
     if (s->coalesced_mmio && !s->coalesced_mmio_ring) {
         s->coalesced_mmio_ring =
             (void *)env->kvm_run + s->coalesced_mmio * PAGE_SIZE;
     }
-#endif
 
     ret = kvm_arch_init_vcpu(env);
     if (ret == 0) {
@@ -401,7 +403,6 @@ static int 
kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
 int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
 {
     int ret = -ENOSYS;
-#ifdef KVM_CAP_COALESCED_MMIO
     KVMState *s = kvm_state;
 
     if (s->coalesced_mmio) {
@@ -412,7 +413,6 @@ int kvm_coalesce_mmio_region(target_phys_addr_t start, 
ram_addr_t size)
 
         ret = kvm_vm_ioctl(s, KVM_REGISTER_COALESCED_MMIO, &zone);
     }
-#endif
 
     return ret;
 }
@@ -420,7 +420,6 @@ int kvm_coalesce_mmio_region(target_phys_addr_t start, 
ram_addr_t size)
 int kvm_uncoalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
 {
     int ret = -ENOSYS;
-#ifdef KVM_CAP_COALESCED_MMIO
     KVMState *s = kvm_state;
 
     if (s->coalesced_mmio) {
@@ -431,7 +430,6 @@ int kvm_uncoalesce_mmio_region(target_phys_addr_t start, 
ram_addr_t size)
 
         ret = kvm_vm_ioctl(s, KVM_UNREGISTER_COALESCED_MMIO, &zone);
     }
-#endif
 
     return ret;
 }
@@ -481,6 +479,18 @@ static int kvm_check_many_ioeventfds(void)
 #endif
 }
 
+static const KVMCapabilityInfo *
+kvm_check_extension_list(KVMState *s, const KVMCapabilityInfo *list)
+{
+    while (list->name) {
+        if (!kvm_check_extension(s, list->value)) {
+            return list;
+        }
+        list++;
+    }
+    return NULL;
+}
+
 static void kvm_set_phys_mem(target_phys_addr_t start_addr, ram_addr_t size,
                              ram_addr_t phys_offset)
 {
@@ -642,6 +652,7 @@ int kvm_init(void)
         "Please upgrade to at least kernel 2.6.29 or recent kvm-kmod\n"
         "(see http://sourceforge.net/projects/kvm).\n";
     KVMState *s;
+    const KVMCapabilityInfo *missing_cap;
     int ret;
     int i;
 
@@ -685,35 +696,19 @@ int kvm_init(void)
         goto err;
     }
 
-    /* initially, KVM allocated its own memory and we had to jump through
-     * hooks to make phys_ram_base point to this.  Modern versions of KVM
-     * just use a user allocated buffer so we can use regular pages
-     * unmodified.  Make sure we have a sufficiently modern version of KVM.
-     */
-    if (!kvm_check_extension(s, KVM_CAP_USER_MEMORY)) {
-        ret = -EINVAL;
-        fprintf(stderr, "kvm does not support KVM_CAP_USER_MEMORY\n%s",
-                upgrade_note);
-        goto err;
+    missing_cap = kvm_check_extension_list(s, kvm_required_capabilites);
+    if (!missing_cap) {
+        missing_cap =
+            kvm_check_extension_list(s, kvm_arch_required_capabilities);
     }
-
-    /* There was a nasty bug in < kvm-80 that prevents memory slots from being
-     * destroyed properly.  Since we rely on this capability, refuse to work
-     * with any kernel without this capability. */
-    if (!kvm_check_extension(s, KVM_CAP_DESTROY_MEMORY_REGION_WORKS)) {
+    if (missing_cap) {
         ret = -EINVAL;
-
-        fprintf(stderr,
-                "KVM kernel module broken (DESTROY_MEMORY_REGION).\n%s",
-                upgrade_note);
+        fprintf(stderr, "kvm does not support %s\n%s",
+                missing_cap->name, upgrade_note);
         goto err;
     }
 
-    s->coalesced_mmio = 0;
-#ifdef KVM_CAP_COALESCED_MMIO
     s->coalesced_mmio = kvm_check_extension(s, KVM_CAP_COALESCED_MMIO);
-    s->coalesced_mmio_ring = NULL;
-#endif
 
     s->broken_set_mem_region = 1;
 #ifdef KVM_CAP_JOIN_MEMORY_REGIONS_WORKS
@@ -845,7 +840,6 @@ static int kvm_handle_internal_error(CPUState *env, struct 
kvm_run *run)
 
 void kvm_flush_coalesced_mmio_buffer(void)
 {
-#ifdef KVM_CAP_COALESCED_MMIO
     KVMState *s = kvm_state;
     if (s->coalesced_mmio_ring) {
         struct kvm_coalesced_mmio_ring *ring = s->coalesced_mmio_ring;
@@ -859,7 +853,6 @@ void kvm_flush_coalesced_mmio_buffer(void)
             ring->first = (ring->first + 1) % KVM_COALESCED_MMIO_MAX;
         }
     }
-#endif
 }
 
 static void do_kvm_cpu_synchronize_state(void *_env)
@@ -1059,13 +1052,7 @@ int kvm_vcpu_ioctl(CPUState *env, int type, ...)
 
 int kvm_has_sync_mmu(void)
 {
-#ifdef KVM_CAP_SYNC_MMU
-    KVMState *s = kvm_state;
-
-    return kvm_check_extension(s, KVM_CAP_SYNC_MMU);
-#else
-    return 0;
-#endif
+    return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
 }
 
 int kvm_has_vcpu_events(void)
diff --git a/kvm.h b/kvm.h
index a971752..ca57517 100644
--- a/kvm.h
+++ b/kvm.h
@@ -32,6 +32,14 @@ extern int kvm_allowed;
 
 struct kvm_run;
 
+typedef struct KVMCapabilityInfo {
+    const char *name;
+    int value;
+} KVMCapabilityInfo;
+
+#define KVM_CAP_INFO(CAP) { "KVM_CAP_" stringify(CAP), KVM_CAP_##CAP }
+#define KVM_CAP_LAST_INFO { NULL, 0 }
+
 /* external API */
 
 int kvm_init(void);
@@ -86,6 +94,8 @@ int kvm_vcpu_ioctl(CPUState *env, int type, ...);
 
 /* Arch specific hooks */
 
+extern const KVMCapabilityInfo kvm_arch_required_capabilities[];
+
 int kvm_arch_post_run(CPUState *env, struct kvm_run *run);
 
 int kvm_arch_handle_exit(CPUState *env, struct kvm_run *run);
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 016b67d..1db8227 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -54,12 +54,17 @@
 #define BUS_MCEERR_AO 5
 #endif
 
+const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
+    KVM_CAP_INFO(SET_TSS_ADDR),
+    KVM_CAP_INFO(EXT_CPUID),
+    KVM_CAP_INFO(MP_STATE),
+    KVM_CAP_LAST_INFO
+};
+
 static bool has_msr_star;
 static bool has_msr_hsave_pa;
 static int lm_capable_kernel;
 
-#ifdef KVM_CAP_EXT_CPUID
-
 static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max)
 {
     struct kvm_cpuid2 *cpuid;
@@ -93,10 +98,6 @@ uint32_t kvm_arch_get_supported_cpuid(CPUState *env, 
uint32_t function,
     uint32_t ret = 0;
     uint32_t cpuid_1_edx;
 
-    if (!kvm_check_extension(env->kvm_state, KVM_CAP_EXT_CPUID)) {
-        return -1U;
-    }
-
     max = 1;
     while ((cpuid = try_get_cpuid(env->kvm_state, max)) == NULL) {
         max *= 2;
@@ -140,30 +141,14 @@ uint32_t kvm_arch_get_supported_cpuid(CPUState *env, 
uint32_t function,
     return ret;
 }
 
-#else
-
-uint32_t kvm_arch_get_supported_cpuid(CPUState *env, uint32_t function,
-                                      uint32_t index, int reg)
-{
-    return -1U;
-}
-
-#endif
-
 #ifdef CONFIG_KVM_PARA
 struct kvm_para_features {
     int cap;
     int feature;
 } para_features[] = {
-#ifdef KVM_CAP_CLOCKSOURCE
     { KVM_CAP_CLOCKSOURCE, KVM_FEATURE_CLOCKSOURCE },
-#endif
-#ifdef KVM_CAP_NOP_IO_DELAY
     { KVM_CAP_NOP_IO_DELAY, KVM_FEATURE_NOP_IO_DELAY },
-#endif
-#ifdef KVM_CAP_PV_MMU
     { KVM_CAP_PV_MMU, KVM_FEATURE_MMU_OP },
-#endif
 #ifdef KVM_CAP_ASYNC_PF
     { KVM_CAP_ASYNC_PF, KVM_FEATURE_ASYNC_PF },
 #endif
@@ -542,15 +527,7 @@ int kvm_arch_init(KVMState *s)
 
     /* create vm86 tss.  KVM uses vm86 mode to emulate 16-bit code
      * directly.  In order to use vm86 mode, a TSS is needed.  Since this
-     * must be part of guest physical memory, we need to allocate it.  Older
-     * versions of KVM just assumed that it would be at the end of physical
-     * memory but that doesn't work with more than 4GB of memory.  We simply
-     * refuse to work with those older versions of KVM. */
-    ret = kvm_check_extension(s, KVM_CAP_SET_TSS_ADDR);
-    if (ret <= 0) {
-        fprintf(stderr, "kvm does not support KVM_CAP_SET_TSS_ADDR\n");
-        return ret;
-    }
+     * must be part of guest physical memory, we need to allocate it. */
 
     /* this address is 3 pages before the bios, and the bios should present
      * as unavaible memory.  FIXME, need to ensure the e820 map deals with
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 3c05630..710eca1 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -37,6 +37,10 @@
     do { } while (0)
 #endif
 
+const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
+    KVM_CAP_LAST_INFO
+};
+
 static int cap_interrupt_unset = false;
 static int cap_interrupt_level = false;
 
diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index b177e10..38823f5 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -70,6 +70,10 @@
 #define SCLP_CMDW_READ_SCP_INFO         0x00020001
 #define SCLP_CMDW_READ_SCP_INFO_FORCED  0x00120001
 
+const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
+    KVM_CAP_LAST_INFO
+};
+
 int kvm_arch_init(KVMState *s)
 {
     return 0;
-- 
1.7.1