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Subject[PATCH 2/3 v11] x86/mm: change the check condition in SEV because a new descriptor is introduced
Date
Originally, those areas described as IORES_DESC_NONE are not mapped
encrypted in SEV when using ioremap(). It checks for a resource that
is not described as IORES_DESC_NONE, which can ensure the reserved
areas are not mapped encrypted when using ioremap().

But now, a new descriptor IORES_DESC_RESERVED has been created for
the reserved areas, similarly, the IORES_DESC_{NONE,RESERVED} should
not be mapped encrypted in SEV when using ioremap().

Therefore, need to modify the check condition in SEV and improve them.

Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
arch/x86/mm/ioremap.c | 59 ++++++++++++++++++++++++++----------------
include/linux/ioport.h | 9 +++++++
2 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index dd73d5d74393..82be5707124b 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -27,9 +27,8 @@

#include "physaddr.h"

-struct ioremap_mem_flags {
- bool system_ram;
- bool desc_other;
+struct ioremap_desc {
+ unsigned int flags;
};

/*
@@ -61,13 +60,13 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
return err;
}

-static bool __ioremap_check_ram(struct resource *res)
+static unsigned int __ioremap_check_ram(struct resource *res)
{
unsigned long start_pfn, stop_pfn;
unsigned long i;

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;
@@ -75,28 +74,44 @@ static bool __ioremap_check_ram(struct resource *res)
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 IORES_MAP_SYSTEM_RAM;
}

- return false;
+ return 0;
}

-static int __ioremap_check_desc_other(struct resource *res)
+/*
+ * NONE and RESERVED should not be mapped encrypted in SEV because there
+ * the whole memory is already encrypted.
+ */
+static unsigned int __ioremap_check_desc(struct resource *res)
{
- return (res->desc != IORES_DESC_NONE);
+ if (!sev_active())
+ return 0;
+
+ switch (res->desc) {
+ case IORES_DESC_NONE:
+ case IORES_DESC_RESERVED:
+ break;
+ default:
+ return IORES_MAP_ENCRYPTED;
+ }
+
+ return 0;
}

static int __ioremap_res_check(struct resource *res, void *arg)
{
- struct ioremap_mem_flags *flags = arg;
+ struct ioremap_desc *desc = arg;

- if (!flags->system_ram)
- flags->system_ram = __ioremap_check_ram(res);
+ if (!(desc->flags & IORES_MAP_SYSTEM_RAM))
+ desc->flags |= __ioremap_check_ram(res);

- if (!flags->desc_other)
- flags->desc_other = __ioremap_check_desc_other(res);
+ if (!(desc->flags & IORES_MAP_ENCRYPTED))
+ desc->flags |= __ioremap_check_desc(res);

- return flags->system_ram && flags->desc_other;
+ return ((desc->flags & (IORES_MAP_SYSTEM_RAM | IORES_MAP_ENCRYPTED)) ==
+ (IORES_MAP_SYSTEM_RAM | IORES_MAP_ENCRYPTED));
}

/*
@@ -105,15 +120,15 @@ static int __ioremap_res_check(struct resource *res, void *arg)
* 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)
+ struct ioremap_desc *desc)
{
u64 start, end;

start = (u64)addr;
end = start + size - 1;
- memset(flags, 0, sizeof(*flags));
+ memset(desc, 0, sizeof(struct ioremap_desc));

- walk_mem_res(start, end, flags, __ioremap_res_check);
+ walk_mem_res(start, end, desc, __ioremap_res_check);
}

/*
@@ -138,7 +153,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_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 ioremap_desc io_desc;
struct vm_struct *area;
enum page_cache_mode new_pcm;
pgprot_t prot;
@@ -157,12 +172,12 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
return NULL;
}

- __ioremap_check_mem(phys_addr, size, &mem_flags);
+ __ioremap_check_mem(phys_addr, size, &io_desc);

/*
* Don't allow anybody to remap normal RAM that we're using..
*/
- if (mem_flags.system_ram) {
+ if (io_desc.flags & IORES_MAP_SYSTEM_RAM) {
WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
&phys_addr, &last_addr);
return NULL;
@@ -200,7 +215,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
* resulting mapping.
*/
prot = PAGE_KERNEL_IO;
- if ((sev_active() && mem_flags.desc_other) || encrypted)
+ if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted)
prot = pgprot_encrypted(prot);

switch (pcm) {
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6ed59de48bd5..5db386cfc2d4 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -12,6 +12,7 @@
#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <linux/types.h>
+#include <linux/bits.h>
/*
* Resources are tree-like, allowing
* nesting etc..
@@ -136,6 +137,14 @@ enum {
IORES_DESC_RESERVED = 8,
};

+/*
+ * Flags controlling ioremap() behavior.
+ */
+enum {
+ IORES_MAP_SYSTEM_RAM = BIT(0),
+ IORES_MAP_ENCRYPTED = BIT(1),
+};
+
/* helpers to define resources */
#define DEFINE_RES_NAMED(_start, _size, _name, _flags) \
{ \
--
2.17.1
\
 
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