[Qemu-devel] [PATCH qemu 1/2] exec, kvm, target-ppc: Move getrampagesize() to common code

[Alexey Kardashevskiy <aik@ozlabs.ru>]

getrampagesize() returns the largest supported page size and mainly
used to know if huge pages are enabled.

However is implemented in target-ppc/kvm.c and not available
in TCG or other architectures.

This renames and moves gethugepagesize() to mmap-alloc.c where
fd-based analog of it is already implemented. This renames and moves
getrampagesize() to exec.c as it seems to be the common place for
helpers like this.

This first user for it is going to be a spapr-pci-host-bridge which
needs to know the largest RAM page size so the guest could try
using bigger IOMMU pages to save memory.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 include/exec/ram_addr.h   |   1 +
 include/qemu/mmap-alloc.h |   2 +
 exec.c                    |  82 ++++++++++++++++++++++++++++++++++++
 target-ppc/kvm.c          | 105 ++--------------------------------------------
 util/mmap-alloc.c         |  25 +++++++++++
 5 files changed, 113 insertions(+), 102 deletions(-)

diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 54d7108a9e..3935cbcfcd 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -91,6 +91,7 @@ typedef struct RAMList {
 } RAMList;
 extern RAMList ram_list;
 
+long qemu_getrampagesize(void);
 ram_addr_t last_ram_offset(void);
 void qemu_mutex_lock_ramlist(void);
 void qemu_mutex_unlock_ramlist(void);
diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
index 933c024ac5..50385e3f81 100644
--- a/include/qemu/mmap-alloc.h
+++ b/include/qemu/mmap-alloc.h
@@ -5,6 +5,8 @@
 
 size_t qemu_fd_getpagesize(int fd);
 
+size_t qemu_mempath_getpagesize(const char *mem_path);
+
 void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared);
 
 void qemu_ram_munmap(void *ptr, size_t size);
diff --git a/exec.c b/exec.c
index 08c558eecf..d73b477a70 100644
--- a/exec.c
+++ b/exec.c
@@ -32,6 +32,7 @@
 #endif
 #include "sysemu/kvm.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/numa.h"
 #include "qemu/timer.h"
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
@@ -1218,6 +1219,87 @@ void qemu_mutex_unlock_ramlist(void)
 }
 
 #ifdef __linux__
+/*
+ * FIXME TOCTTOU: this iterates over memory backends' mem-path, which
+ * may or may not name the same files / on the same filesystem now as
+ * when we actually open and map them.  Iterate over the file
+ * descriptors instead, and use qemu_fd_getpagesize().
+ */
+static int find_max_supported_pagesize(Object *obj, void *opaque)
+{
+    char *mem_path;
+    long *hpsize_min = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_MEMORY_BACKEND)) {
+        mem_path = object_property_get_str(obj, "mem-path", NULL);
+        if (mem_path) {
+            long hpsize = qemu_mempath_getpagesize(mem_path);
+            if (hpsize < *hpsize_min) {
+                *hpsize_min = hpsize;
+            }
+        } else {
+            *hpsize_min = getpagesize();
+        }
+    }
+
+    return 0;
+}
+
+long qemu_getrampagesize(void)
+{
+    long hpsize = LONG_MAX;
+    long mainrampagesize;
+    Object *memdev_root;
+
+    if (mem_path) {
+        mainrampagesize = qemu_mempath_getpagesize(mem_path);
+    } else {
+        mainrampagesize = getpagesize();
+    }
+
+    /* it's possible we have memory-backend objects with
+     * hugepage-backed RAM. these may get mapped into system
+     * address space via -numa parameters or memory hotplug
+     * hooks. we want to take these into account, but we
+     * also want to make sure these supported hugepage
+     * sizes are applicable across the entire range of memory
+     * we may boot from, so we take the min across all
+     * backends, and assume normal pages in cases where a
+     * backend isn't backed by hugepages.
+     */
+    memdev_root = object_resolve_path("/objects", NULL);
+    if (memdev_root) {
+        object_child_foreach(memdev_root, find_max_supported_pagesize, &hpsize);
+    }
+    if (hpsize == LONG_MAX) {
+        /* No additional memory regions found ==> Report main RAM page size */
+        return mainrampagesize;
+    }
+
+    /* If NUMA is disabled or the NUMA nodes are not backed with a
+     * memory-backend, then there is at least one node using "normal" RAM,
+     * so if its page size is smaller we have got to report that size instead.
+     */
+    if (hpsize > mainrampagesize &&
+        (nb_numa_nodes == 0 || numa_info[0].node_memdev == NULL)) {
+        static bool warned;
+        if (!warned) {
+            error_report("Huge page support disabled (n/a for main memory).");
+            warned = true;
+        }
+        return mainrampagesize;
+    }
+
+    return hpsize;
+}
+#else
+long qemu_getrampagesize(void)
+{
+    return getpagesize();
+}
+#endif
+
+#ifdef __linux__
 static int64_t get_file_size(int fd)
 {
     int64_t size = lseek(fd, 0, SEEK_END);
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 6e91a4d8bb..e0abffa8ad 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -42,6 +42,7 @@
 #include "trace.h"
 #include "exec/gdbstub.h"
 #include "exec/memattrs.h"
+#include "exec/ram_addr.h"
 #include "sysemu/hostmem.h"
 #include "qemu/cutils.h"
 #if defined(TARGET_PPC64)
@@ -325,106 +326,6 @@ static void kvm_get_smmu_info(PowerPCCPU *cpu, struct kvm_ppc_smmu_info *info)
     kvm_get_fallback_smmu_info(cpu, info);
 }
 
-static long gethugepagesize(const char *mem_path)
-{
-    struct statfs fs;
-    int ret;
-
-    do {
-        ret = statfs(mem_path, &fs);
-    } while (ret != 0 && errno == EINTR);
-
-    if (ret != 0) {
-        fprintf(stderr, "Couldn't statfs() memory path: %s\n",
-                strerror(errno));
-        exit(1);
-    }
-
-#define HUGETLBFS_MAGIC       0x958458f6
-
-    if (fs.f_type != HUGETLBFS_MAGIC) {
-        /* Explicit mempath, but it's ordinary pages */
-        return getpagesize();
-    }
-
-    /* It's hugepage, return the huge page size */
-    return fs.f_bsize;
-}
-
-/*
- * FIXME TOCTTOU: this iterates over memory backends' mem-path, which
- * may or may not name the same files / on the same filesystem now as
- * when we actually open and map them.  Iterate over the file
- * descriptors instead, and use qemu_fd_getpagesize().
- */
-static int find_max_supported_pagesize(Object *obj, void *opaque)
-{
-    char *mem_path;
-    long *hpsize_min = opaque;
-
-    if (object_dynamic_cast(obj, TYPE_MEMORY_BACKEND)) {
-        mem_path = object_property_get_str(obj, "mem-path", NULL);
-        if (mem_path) {
-            long hpsize = gethugepagesize(mem_path);
-            if (hpsize < *hpsize_min) {
-                *hpsize_min = hpsize;
-            }
-        } else {
-            *hpsize_min = getpagesize();
-        }
-    }
-
-    return 0;
-}
-
-static long getrampagesize(void)
-{
-    long hpsize = LONG_MAX;
-    long mainrampagesize;
-    Object *memdev_root;
-
-    if (mem_path) {
-        mainrampagesize = gethugepagesize(mem_path);
-    } else {
-        mainrampagesize = getpagesize();
-    }
-
-    /* it's possible we have memory-backend objects with
-     * hugepage-backed RAM. these may get mapped into system
-     * address space via -numa parameters or memory hotplug
-     * hooks. we want to take these into account, but we
-     * also want to make sure these supported hugepage
-     * sizes are applicable across the entire range of memory
-     * we may boot from, so we take the min across all
-     * backends, and assume normal pages in cases where a
-     * backend isn't backed by hugepages.
-     */
-    memdev_root = object_resolve_path("/objects", NULL);
-    if (memdev_root) {
-        object_child_foreach(memdev_root, find_max_supported_pagesize, &hpsize);
-    }
-    if (hpsize == LONG_MAX) {
-        /* No additional memory regions found ==> Report main RAM page size */
-        return mainrampagesize;
-    }
-
-    /* If NUMA is disabled or the NUMA nodes are not backed with a
-     * memory-backend, then there is at least one node using "normal" RAM,
-     * so if its page size is smaller we have got to report that size instead.
-     */
-    if (hpsize > mainrampagesize &&
-        (nb_numa_nodes == 0 || numa_info[0].node_memdev == NULL)) {
-        static bool warned;
-        if (!warned) {
-            error_report("Huge page support disabled (n/a for main memory).");
-            warned = true;
-        }
-        return mainrampagesize;
-    }
-
-    return hpsize;
-}
-
 static bool kvm_valid_page_size(uint32_t flags, long rampgsize, uint32_t shift)
 {
     if (!(flags & KVM_PPC_PAGE_SIZES_REAL)) {
@@ -454,7 +355,7 @@ static void kvm_fixup_page_sizes(PowerPCCPU *cpu)
         has_smmu_info = true;
     }
 
-    rampagesize = getrampagesize();
+    rampagesize = qemu_getrampagesize();
 
     /* Convert to QEMU form */
     memset(&env->sps, 0, sizeof(env->sps));
@@ -2177,7 +2078,7 @@ uint64_t kvmppc_rma_size(uint64_t current_size, unsigned int hash_shift)
     /* Find the largest hardware supported page size that's less than
      * or equal to the (logical) backing page size of guest RAM */
     kvm_get_smmu_info(POWERPC_CPU(first_cpu), &info);
-    rampagesize = getrampagesize();
+    rampagesize = qemu_getrampagesize();
     best_page_shift = 0;
 
     for (i = 0; i < KVM_PPC_PAGE_SIZES_MAX_SZ; i++) {
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 5a85aa3c89..564c79109c 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -39,6 +39,31 @@ size_t qemu_fd_getpagesize(int fd)
     return getpagesize();
 }
 
+size_t qemu_mempath_getpagesize(const char *mem_path)
+{
+#ifdef CONFIG_LINUX
+    struct statfs fs;
+    int ret;
+
+    do {
+        ret = statfs(mem_path, &fs);
+    } while (ret != 0 && errno == EINTR);
+
+    if (ret != 0) {
+        fprintf(stderr, "Couldn't statfs() memory path: %s\n",
+                strerror(errno));
+        exit(1);
+    }
+
+    if (fs.f_type == HUGETLBFS_MAGIC) {
+        /* It's hugepage, return the huge page size */
+        return fs.f_bsize;
+    }
+#endif
+
+    return getpagesize();
+}
+
 void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
 {
     /*
-- 
2.11.0