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SubjectRe: [PATCH 1/2 RESEND v10] x86/mm, resource: add a new I/O resource descriptor 'IORES_DESC_RESERVED'
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在 2019年04月15日 23:41, Borislav Petkov 写道:
> On Mon, Apr 15, 2019 at 08:22:22PM +0800, lijiang wrote:
>> They are different problems.
>
> Aha, so we're getting closer. You should've lead with that!
>
>> The first problem is that passes the e820 reserved ranges to the second kernel,
>
> Passes or *doesn't* pass?
>
> Because from all the staring, it wants to pass the reserved ranges.
>
>> for this case, it is good enough to use the IORES_DESC_RESERVED, which
>> can ensure that exactly matches the reserved resource ranges when
>> walking through iomem resources.
>
> Ok.
>
>> The second problem is about the SEV case. Now, the IORES_DESC_RESERVED has been
>> created for the reserved areas, therefore the check needs to be expanded so that
>> these areas are not mapped encrypted when using ioremap().
>>
>> +static int __ioremap_check_desc_none_and_reserved(struct resource *res)
>
> That name is crap. If you need to add another desc type, it becomes
> wrong again. And that whole code around flags->desc_other is just silly:
>
> Make that machinery around it something like this:
>
> struct ioremap_desc {
> u64 flags;
> };
>
> instead of "struct ioremap_mem_flags" and that struct ioremap_desc is an
> ioremap descriptor which will carry all kinds of settings. system_ram
> can then be a simple flag too.
>
> __ioremap_caller() will hand it down to __ioremap_check_mem() etc
> and there it will set flags like IOREMAP_DESC_MAP_ENCRYPTED or
> IOREMAP_DESC_MAP_DECRYPTED and this way you'll have it explicit and
> clear in __ioremap_caller():
>
> if ((sev_active() &&
> (io_desc.flags & IOREMAP_DESC_MAP_ENCRYPTED)) ||
> encrypted)
> prot = pgprot_encrypted(prot);
>
> But that would need a pre-patch which does that conversion.
>
Thanks for your comment.

Based on the above description, i made a draft patch, please refer to it. But it
seems that the code has been changed a lot.

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 0029604af8a4..04217b61635e 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 {
+ u64 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 long __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 IOREMAP_DESC_MAP_NONE;

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 IOREMAP_DESC_MAP_SYSTEM_RAM_USING;
}

- return false;
+ return IOREMAP_DESC_MAP_NONE;
}

-static int __ioremap_check_desc_other(struct resource *res)
+/*
+ * Originally, these areas described as IORES_DESC_NONE are not mapped
+ * as encrypted when using ioremap(), for example, E820_TYPE_{RESERVED,
+ * RESERVED_KERN,RAM,UNUSABLE}, etc. It checks for a resource that is
+ * not described as IORES_DESC_NONE, which can make sure the reserved
+ * areas are not mapped as encrypted when using ioremap().
+ *
+ * Now IORES_DESC_RESERVED has been created for the reserved areas so
+ * the check needs to be expanded so that these areas are not mapped
+ * encrypted when using ioremap().
+ */
+static unsigned long __ioremap_check_desc(struct resource *res)
{
- return (res->desc != IORES_DESC_NONE);
+ if ((res->desc != IORES_DESC_NONE) &&
+ (res->desc != IORES_DESC_RESERVED))
+ return IOREMAP_DESC_MAP_ENCRYPTED;
+
+ return IOREMAP_DESC_MAP_NONE;
}

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 & IOREMAP_DESC_MAP_SYSTEM_RAM_USING))
+ desc->flags |= __ioremap_check_ram(res);

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

- return flags->system_ram && flags->desc_other;
+ return ((desc->flags & IOREMAP_DESC_MAP_SYSTEM_RAM_USING) &&
+ (desc->flags & IOREMAP_DESC_MAP_ENCRYPTED))
}

/*
@@ -105,13 +120,13 @@ 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(*desc));

walk_mem_res(start, end, flags, __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 & IOREMAP_DESC_MAP_SYSTEM_RAM_USING) {
WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
&phys_addr, &last_addr);
return NULL;
@@ -200,7 +215,9 @@ 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 ((sev_active() &&
+ (io_desc.flags & IOREMAP_DESC_MAP_ENCRYPTED)) ||
+ encrypted)
prot = pgprot_encrypted(prot);

switch (pcm) {
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6ed59de48bd5..48b2d21ad9e5 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -136,6 +136,15 @@ enum {
IORES_DESC_RESERVED = 8,
};

+/*
+ * IORemap Descriptors Helper
+ */
+enum {
+ IOREMAP_DESC_MAP_NONE = 0,
+ IOREMAP_DESC_MAP_SYSTEM_RAM_USING = 1,
+ IOREMAP_DESC_MAP_ENCRYPTED = 2,
+};
+
/* helpers to define resources */
#define DEFINE_RES_NAMED(_start, _size, _name, _flags) \
{ \
Are you sure about this changes? Or Do other reviewers have any suggestions?

Thanks.

>> Maybe i should split it into two patches. The change of
>> __ioremap_check_desc_none_and_reserved() should be a separate patch.
>> Any idea?
>
> See above and yes, definitely separate patches.
>
OK. Thank you very much.

Lianbo

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