On 6/21/2017 2:37 AM, Thomas Gleixner wrote:
On Fri, 16 Jun 2017, Tom Lendacky 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, however, this will result
in the mapping having the encryption bit set when it is expected that
an ioremap() should not have the encryption bit set. So only use the
phys_to_virt() function if SME is not active
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
arch/x86/mm/ioremap.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 4c1b5fd..a382ba9 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>
@@ -106,9 +107,11 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
}
/*
- * Don't remap the low PCI/ISA area, it's always mapped..
+ * Don't remap the low PCI/ISA area, it's always mapped.
+ * But if SME is active, skip this so that the encryption bit
+ * doesn't get set.
*/
- if (is_ISA_range(phys_addr, last_addr))
+ if (is_ISA_range(phys_addr, last_addr) && !sme_active())
return (__force void __iomem *)phys_to_virt(phys_addr);
More thoughts about that.
Making this conditional on !sme_active() is not the best idea. I'd rather
remove that whole thing and make it unconditional so the code pathes get
always exercised and any subtle wreckage is detected on a broader base and
not only on that hard to access and debug SME capable machine owned by Joe
User.
Ok, that sounds good. I'll remove the check and usage of phys_to_virt()
and update the changelog with additional detail about that.
Thanks,
Tom
Thanks,
tglx
