From: David Hildenbrand <david@redhat.com> To: linux-kernel@vger.kernel.org Cc: David Hildenbrand <david@redhat.com>, Arnd Bergmann <arnd@arndb.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>, "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Dan Williams <dan.j.williams@intel.com>, Hanjun Guo <guohanjun@huawei.com>, Andy Shevchenko <andy.shevchenko@gmail.com>, virtualization@lists.linux-foundation.org, linux-mm@kvack.org Subject: [PATCH v5 1/3] kernel/resource: clean up and optimize iomem_is_exclusive() Date: Mon, 20 Sep 2021 16:28:54 +0200 [thread overview] Message-ID: <20210920142856.17758-2-david@redhat.com> (raw) In-Reply-To: <20210920142856.17758-1-david@redhat.com> We end up traversing subtrees of ranges we are not interested in; let's optimize this case, skipping such subtrees, cleaning up the function a bit. For example, in the following configuration (/proc/iomem): 00000000-00000fff : Reserved 00001000-00057fff : System RAM 00058000-00058fff : Reserved 00059000-0009cfff : System RAM 0009d000-000fffff : Reserved 000a0000-000bffff : PCI Bus 0000:00 000c0000-000c3fff : PCI Bus 0000:00 000c4000-000c7fff : PCI Bus 0000:00 000c8000-000cbfff : PCI Bus 0000:00 000cc000-000cffff : PCI Bus 0000:00 000d0000-000d3fff : PCI Bus 0000:00 000d4000-000d7fff : PCI Bus 0000:00 000d8000-000dbfff : PCI Bus 0000:00 000dc000-000dffff : PCI Bus 0000:00 000e0000-000e3fff : PCI Bus 0000:00 000e4000-000e7fff : PCI Bus 0000:00 000e8000-000ebfff : PCI Bus 0000:00 000ec000-000effff : PCI Bus 0000:00 000f0000-000fffff : PCI Bus 0000:00 000f0000-000fffff : System ROM 00100000-3fffffff : System RAM 40000000-403fffff : Reserved 40000000-403fffff : pnp 00:00 40400000-80a79fff : System RAM ... We don't have to look at any children of "0009d000-000fffff : Reserved" if we can just skip these 15 items directly because the parent range is not of interest. Reviewed-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- kernel/resource.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/kernel/resource.c b/kernel/resource.c index ca9f5198a01f..2999f57da38c 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -73,6 +73,18 @@ static struct resource *next_resource(struct resource *p) return p->sibling; } +static struct resource *next_resource_skip_children(struct resource *p) +{ + while (!p->sibling && p->parent) + p = p->parent; + return p->sibling; +} + +#define for_each_resource(_root, _p, _skip_children) \ + for ((_p) = (_root)->child; (_p); \ + (_p) = (_skip_children) ? next_resource_skip_children(_p) : \ + next_resource(_p)) + static void *r_next(struct seq_file *m, void *v, loff_t *pos) { struct resource *p = v; @@ -1712,10 +1724,9 @@ static int strict_iomem_checks; */ bool iomem_is_exclusive(u64 addr) { - struct resource *p = &iomem_resource; - bool err = false; - loff_t l; + bool skip_children = false, err = false; int size = PAGE_SIZE; + struct resource *p; if (!strict_iomem_checks) return false; @@ -1723,15 +1734,19 @@ bool iomem_is_exclusive(u64 addr) addr = addr & PAGE_MASK; read_lock(&resource_lock); - for (p = p->child; p ; p = r_next(NULL, p, &l)) { + for_each_resource(&iomem_resource, p, skip_children) { /* * We can probably skip the resources without * IORESOURCE_IO attribute? */ if (p->start >= addr + size) break; - if (p->end < addr) + if (p->end < addr) { + skip_children = true; continue; + } + skip_children = false; + /* * A resource is exclusive if IORESOURCE_EXCLUSIVE is set * or CONFIG_IO_STRICT_DEVMEM is enabled and the -- 2.31.1
WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com> To: linux-kernel@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de>, "Michael S. Tsirkin" <mst@redhat.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, Andy Shevchenko <andy.shevchenko@gmail.com>, Hanjun Guo <guohanjun@huawei.com>, Andrew Morton <akpm@linux-foundation.org>, Dan Williams <dan.j.williams@intel.com> Subject: [PATCH v5 1/3] kernel/resource: clean up and optimize iomem_is_exclusive() Date: Mon, 20 Sep 2021 16:28:54 +0200 [thread overview] Message-ID: <20210920142856.17758-2-david@redhat.com> (raw) In-Reply-To: <20210920142856.17758-1-david@redhat.com> We end up traversing subtrees of ranges we are not interested in; let's optimize this case, skipping such subtrees, cleaning up the function a bit. For example, in the following configuration (/proc/iomem): 00000000-00000fff : Reserved 00001000-00057fff : System RAM 00058000-00058fff : Reserved 00059000-0009cfff : System RAM 0009d000-000fffff : Reserved 000a0000-000bffff : PCI Bus 0000:00 000c0000-000c3fff : PCI Bus 0000:00 000c4000-000c7fff : PCI Bus 0000:00 000c8000-000cbfff : PCI Bus 0000:00 000cc000-000cffff : PCI Bus 0000:00 000d0000-000d3fff : PCI Bus 0000:00 000d4000-000d7fff : PCI Bus 0000:00 000d8000-000dbfff : PCI Bus 0000:00 000dc000-000dffff : PCI Bus 0000:00 000e0000-000e3fff : PCI Bus 0000:00 000e4000-000e7fff : PCI Bus 0000:00 000e8000-000ebfff : PCI Bus 0000:00 000ec000-000effff : PCI Bus 0000:00 000f0000-000fffff : PCI Bus 0000:00 000f0000-000fffff : System ROM 00100000-3fffffff : System RAM 40000000-403fffff : Reserved 40000000-403fffff : pnp 00:00 40400000-80a79fff : System RAM ... We don't have to look at any children of "0009d000-000fffff : Reserved" if we can just skip these 15 items directly because the parent range is not of interest. Reviewed-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- kernel/resource.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/kernel/resource.c b/kernel/resource.c index ca9f5198a01f..2999f57da38c 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -73,6 +73,18 @@ static struct resource *next_resource(struct resource *p) return p->sibling; } +static struct resource *next_resource_skip_children(struct resource *p) +{ + while (!p->sibling && p->parent) + p = p->parent; + return p->sibling; +} + +#define for_each_resource(_root, _p, _skip_children) \ + for ((_p) = (_root)->child; (_p); \ + (_p) = (_skip_children) ? next_resource_skip_children(_p) : \ + next_resource(_p)) + static void *r_next(struct seq_file *m, void *v, loff_t *pos) { struct resource *p = v; @@ -1712,10 +1724,9 @@ static int strict_iomem_checks; */ bool iomem_is_exclusive(u64 addr) { - struct resource *p = &iomem_resource; - bool err = false; - loff_t l; + bool skip_children = false, err = false; int size = PAGE_SIZE; + struct resource *p; if (!strict_iomem_checks) return false; @@ -1723,15 +1734,19 @@ bool iomem_is_exclusive(u64 addr) addr = addr & PAGE_MASK; read_lock(&resource_lock); - for (p = p->child; p ; p = r_next(NULL, p, &l)) { + for_each_resource(&iomem_resource, p, skip_children) { /* * We can probably skip the resources without * IORESOURCE_IO attribute? */ if (p->start >= addr + size) break; - if (p->end < addr) + if (p->end < addr) { + skip_children = true; continue; + } + skip_children = false; + /* * A resource is exclusive if IORESOURCE_EXCLUSIVE is set * or CONFIG_IO_STRICT_DEVMEM is enabled and the -- 2.31.1 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-09-20 14:30 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-20 14:28 [PATCH v5 0/3] virtio-mem: disallow mapping virtio-mem memory via /dev/mem David Hildenbrand 2021-09-20 14:28 ` David Hildenbrand 2021-09-20 14:28 ` David Hildenbrand [this message] 2021-09-20 14:28 ` [PATCH v5 1/3] kernel/resource: clean up and optimize iomem_is_exclusive() David Hildenbrand 2021-09-20 14:28 ` [PATCH v5 2/3] kernel/resource: disallow access to exclusive system RAM regions David Hildenbrand 2021-09-20 14:28 ` David Hildenbrand 2021-09-20 14:28 ` [PATCH v5 3/3] virtio-mem: disallow mapping virtio-mem memory via /dev/mem David Hildenbrand 2021-09-20 14:28 ` David Hildenbrand
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