From: Tom Lendacky <thomas.lendacky@xxxxxxx>
In order for memory pages to be properly mapped when SEV is active, we
need to use the PAGE_KERNEL protection attribute as the base protection.
This will insure that memory mapping of, e.g. ACPI tables, receives the
proper mapping attributes.
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
arch/x86/mm/ioremap.c | 8 ++++++++
include/linux/mm.h | 1 +
kernel/resource.c | 40 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 49 insertions(+)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index c400ab5..481c999 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -151,7 +151,15 @@ 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() && page_is_mem(pfn))
+ prot = __pgprot(pgprot_val(prot) | _PAGE_ENC);
+
switch (pcm) {
case _PAGE_CACHE_MODE_UC:
default:
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b84615b..825df27 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -445,6 +445,7 @@ static inline int get_page_unless_zero(struct page *page)
}
extern int page_is_ram(unsigned long pfn);
+extern int page_is_mem(unsigned long pfn);
enum {
REGION_INTERSECTS,
diff --git a/kernel/resource.c b/kernel/resource.c
index 9b5f044..db56ba3 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -518,6 +518,46 @@ int __weak page_is_ram(unsigned long pfn)
}
EXPORT_SYMBOL_GPL(page_is_ram);
+/*
+ * This function returns true if the target memory is marked as
+ * IORESOURCE_MEM and IORESOUCE_BUSY and described as other than
+ * IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
+ */
+static int walk_mem_range(unsigned long start_pfn, unsigned long nr_pages)
+{
+ struct resource res;
+ unsigned long pfn, end_pfn;
+ u64 orig_end;
+ int ret = -1;
+
+ res.start = (u64) start_pfn << PAGE_SHIFT;
+ res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
+ res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ orig_end = res.end;
+ while ((res.start < res.end) &&
+ (find_next_iomem_res(&res, IORES_DESC_NONE, true) >= 0)) {
+ pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ end_pfn = (res.end + 1) >> PAGE_SHIFT;
+ if (end_pfn > pfn)
+ ret = (res.desc != IORES_DESC_NONE) ? 1 : 0;
+ if (ret)
+ break;
+ res.start = res.end + 1;
+ res.end = orig_end;
+ }
+ return ret;
+}
+
+/*
+ * This generic page_is_mem() returns true if specified address is
+ * registered as memory in iomem_resource list.
+ */
+int __weak page_is_mem(unsigned long pfn)
+{
+ return walk_mem_range(pfn, 1) == 1;
+}
+EXPORT_SYMBOL_GPL(page_is_mem);
+
/**
* region_intersects() - determine intersection of region with known resources
* @start: region start address
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