x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages

In order for memory pages to be properly mapped when SEV is active, it's
necessary to use the PAGE_KERNEL protection attribute as the base
protection.  This ensures that memory mapping of, e.g. ACPI tables,
receives the proper mapping attributes.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: kvm@vger.kernel.org
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20171020143059.3291-11-brijesh.singh@amd.com

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 52cc0f4ed4942e3f0ffe25d0ed049609a0a972ca..6e4573b1da341bd41095b11a692afcba51e4b850 100644 (file)
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -27,6 +27,11 @@
 
 #include "physaddr.h"
 
+struct ioremap_mem_flags {
+       bool system_ram;
+       bool desc_other;
+};
+
 /*
  * Fix up the linear direct mapping of the kernel to avoid cache attribute
  * conflicts.
@@ -56,17 +61,59 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
        return err;
 }
 
-static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,
-                              void *arg)
+static bool __ioremap_check_ram(struct resource *res)
 {
+       unsigned long start_pfn, stop_pfn;
        unsigned long i;
 
-       for (i = 0; i < nr_pages; ++i)
-               if (pfn_valid(start_pfn + i) &&
-                   !PageReserved(pfn_to_page(start_pfn + i)))
-                       return 1;
+       if ((res->flags & IORESOURCE_SYSTEM_RAM) != IORESOURCE_SYSTEM_RAM)
+               return false;
 
-       return 0;
+       start_pfn = (res->start + PAGE_SIZE - 1) >> PAGE_SHIFT;
+       stop_pfn = (res->end + 1) >> PAGE_SHIFT;
+       if (stop_pfn > start_pfn) {
+               for (i = 0; i < (stop_pfn - start_pfn); ++i)
+                       if (pfn_valid(start_pfn + i) &&
+                           !PageReserved(pfn_to_page(start_pfn + i)))
+                               return true;
+       }
+
+       return false;
+}
+
+static int __ioremap_check_desc_other(struct resource *res)
+{
+       return (res->desc != IORES_DESC_NONE);
+}
+
+static int __ioremap_res_check(struct resource *res, void *arg)
+{
+       struct ioremap_mem_flags *flags = arg;
+
+       if (!flags->system_ram)
+               flags->system_ram = __ioremap_check_ram(res);
+
+       if (!flags->desc_other)
+               flags->desc_other = __ioremap_check_desc_other(res);
+
+       return flags->system_ram && flags->desc_other;
+}
+
+/*
+ * To avoid multiple resource walks, this function walks resources marked as
+ * IORESOURCE_MEM and IORESOURCE_BUSY and looking for system RAM and/or a
+ * resource described not as IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
+ */
+static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
+                               struct ioremap_mem_flags *flags)
+{
+       u64 start, end;
+
+       start = (u64)addr;
+       end = start + size - 1;
+       memset(flags, 0, sizeof(*flags));
+
+       walk_mem_res(start, end, flags, __ioremap_res_check);
 }
 
 /*
@@ -87,9 +134,10 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
                unsigned long size, enum page_cache_mode pcm, void *caller)
 {
        unsigned long offset, vaddr;
-       resource_size_t pfn, last_pfn, last_addr;
+       resource_size_t last_addr;
        const resource_size_t unaligned_phys_addr = phys_addr;
        const unsigned long unaligned_size = size;
+       struct ioremap_mem_flags mem_flags;
        struct vm_struct *area;
        enum page_cache_mode new_pcm;
        pgprot_t prot;
@@ -108,13 +156,12 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
                return NULL;
        }
 
+       __ioremap_check_mem(phys_addr, size, &mem_flags);
+
        /*
         * Don't allow anybody to remap normal RAM that we're using..
         */
-       pfn      = phys_addr >> PAGE_SHIFT;
-       last_pfn = last_addr >> PAGE_SHIFT;
-       if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
-                                         __ioremap_check_ram) == 1) {
+       if (mem_flags.system_ram) {
                WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
                          &phys_addr, &last_addr);
                return NULL;
@@ -146,7 +193,15 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
                pcm = new_pcm;
        }
 
+       /*
+        * If the page being mapped is in memory and SEV is active then
+        * make sure the memory encryption attribute is enabled in the
+        * resulting mapping.
+        */
        prot = PAGE_KERNEL_IO;
+       if (sev_active() && mem_flags.desc_other)
+               prot = pgprot_encrypted(prot);
+
        switch (pcm) {
        case _PAGE_CACHE_MODE_UC:
        default:

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index c0070d7c4b9992ebfedea093a73d5f38281a359c..93b4183cf53d4ed45491edf144eec30a5ea8015e 100644 (file)
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -271,6 +271,9 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
                void *arg, int (*func)(unsigned long, unsigned long, void *));
 extern int
+walk_mem_res(u64 start, u64 end, void *arg,
+            int (*func)(struct resource *, void *));
+extern int
 walk_system_ram_res(u64 start, u64 end, void *arg,
                    int (*func)(struct resource *, void *));
 extern int

diff --git a/kernel/resource.c b/kernel/resource.c
index 8430042fa77b18800342ff46a91358f1d73d96db..54ba6de3757c7ebdc83ad7f6c5b3d22b9d20f600 100644 (file)
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -397,6 +397,8 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc,
                res->start = p->start;
        if (res->end > p->end)
                res->end = p->end;
+       res->flags = p->flags;
+       res->desc = p->desc;
        return 0;
 }
 
@@ -467,6 +469,23 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
                                     arg, func);
 }
 
+/*
+ * This function calls the @func callback against all memory ranges, which
+ * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.
+ */
+int walk_mem_res(u64 start, u64 end, void *arg,
+                int (*func)(struct resource *, void *))
+{
+       struct resource res;
+
+       res.start = start;
+       res.end = end;
+       res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+
+       return __walk_iomem_res_desc(&res, IORES_DESC_NONE, true,
+                                    arg, func);
+}
+
 #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
 
 /*