On 7/10/2017 11:58 PM, Brian Gerst wrote: > On Mon, Jul 10, 2017 at 3:50 PM, Tom Lendacky <thomas.lendacky at amd.com> wrote: >> On 7/8/2017 7:57 AM, Brian Gerst wrote: >>> >>> On Fri, Jul 7, 2017 at 9:39 AM, Tom Lendacky <thomas.lendacky at amd.com> >>> wrote: >>>> >>>> Currently there is a check if the address being mapped is in the ISA >>>> range (is_ISA_range()), and if it is, then phys_to_virt() is used to >>>> perform the mapping. When SME is active, the default is to add pagetable >>>> mappings with the encryption bit set unless specifically overridden. The >>>> resulting pagetable mapping from phys_to_virt() will result in a mapping >>>> that has the encryption bit set. With SME, the use of ioremap() is >>>> intended to generate pagetable mappings that do not have the encryption >>>> bit set through the use of the PAGE_KERNEL_IO protection value. >>>> >>>> Rather than special case the SME scenario, remove the ISA range check and >>>> usage of phys_to_virt() and have ISA range mappings continue through the >>>> remaining ioremap() path. >>>> >>>> Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com> >>>> --- >>>> arch/x86/mm/ioremap.c | 7 +------ >>>> 1 file changed, 1 insertion(+), 6 deletions(-) >>>> >>>> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c >>>> index 4c1b5fd..bfc3e2d 100644 >>>> --- a/arch/x86/mm/ioremap.c >>>> +++ b/arch/x86/mm/ioremap.c >>>> @@ -13,6 +13,7 @@ >>>> #include <linux/slab.h> >>>> #include <linux/vmalloc.h> >>>> #include <linux/mmiotrace.h> >>>> +#include <linux/mem_encrypt.h> >>>> >>>> #include <asm/set_memory.h> >>>> #include <asm/e820/api.h> >>>> @@ -106,12 +107,6 @@ static void __iomem >>>> *__ioremap_caller(resource_size_t phys_addr, >>>> } >>>> >>>> /* >>>> - * Don't remap the low PCI/ISA area, it's always mapped.. >>>> - */ >>>> - if (is_ISA_range(phys_addr, last_addr)) >>>> - return (__force void __iomem *)phys_to_virt(phys_addr); >>>> - >>>> - /* >>>> * Don't allow anybody to remap normal RAM that we're using.. >>>> */ >>>> pfn = phys_addr >> PAGE_SHIFT; >>>> >>> >>> Removing this also affects 32-bit, which is more likely to access >>> legacy devices in this range. Put in a check for SME instead >> >> >> I originally had a check for SME here in a previous version of the >> patch. Thomas Gleixner recommended removing the check so that the code >> path was always exercised regardless of the state of SME in order to >> better detect issues: >> >> http://marc.info/?l=linux-kernel&m=149803067811436&w=2 >> >> Thanks, >> Tom > > Looking a bit closer, this shortcut doesn't set the caching > attributes. So it's probably best to get rid of it anyways. Also > note, there is a corresponding check in iounmap(). Good catch. I'll update the patch to include the removal of the ISA checks in the iounmap() path as well. Thanks, Tom > > -- > Brian Gerst >
