Re: [RFC Part1 PATCH v3 11/17] x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages
On 8/1/2017 11:02 PM, Borislav Petkov wrote:
On Mon, Jul 24, 2017 at 02:07:51PM -0500, Brijesh Singh wrote:
From: Tom Lendacky
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
Signed-off-by: Brijesh Singh
---
arch/x86/mm/ioremap.c | 28
include/linux/ioport.h | 3 +++
kernel/resource.c | 17 +
3 files changed, 48 insertions(+)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index c0be7cf..7b27332 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -69,6 +69,26 @@ static int __ioremap_check_ram(unsigned long start_pfn,
unsigned long nr_pages,
return 0;
}
+static int __ioremap_res_desc_other(struct resource *res, void *arg)
+{
+ return (res->desc != IORES_DESC_NONE);
+}
+
+/*
+ * This function returns true if the target memory is marked as
+ * IORESOURCE_MEM and IORESOURCE_BUSY and described as other than
+ * IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
+ */
+static bool __ioremap_check_if_mem(resource_size_t addr, unsigned long size)
+{
+ u64 start, end;
+
+ start = (u64)addr;
+ end = start + size - 1;
+
+ return (walk_mem_res(start, end, NULL, __ioremap_res_desc_other) == 1);
+}
+
/*
* Remap an arbitrary physical address space into the kernel virtual
* address space. It transparently creates kernel huge I/O mapping when
@@ -146,7 +166,15 @@ 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() && __ioremap_check_if_mem(phys_addr, size))
+ prot = pgprot_encrypted(prot);
Hmm, so this function already does walk_system_ram_range() a bit
earlier and now on SEV systems we're going to do it again. Can we make
walk_system_ram_range() return a distinct value for SEV systems and act
accordingly in __ioremap_caller() instead of repeating the operation?
It looks to me like we could...
Let me look into this. I can probably come up with something that does
the walk once.
Thanks,
Tom
Re: [RFC Part1 PATCH v3 11/17] x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages
On Mon, Jul 24, 2017 at 02:07:51PM -0500, Brijesh Singh wrote:
> From: Tom Lendacky
>
> 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
> Signed-off-by: Brijesh Singh
> ---
> arch/x86/mm/ioremap.c | 28
> include/linux/ioport.h | 3 +++
> kernel/resource.c | 17 +
> 3 files changed, 48 insertions(+)
>
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index c0be7cf..7b27332 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -69,6 +69,26 @@ static int __ioremap_check_ram(unsigned long start_pfn,
> unsigned long nr_pages,
> return 0;
> }
>
> +static int __ioremap_res_desc_other(struct resource *res, void *arg)
> +{
> + return (res->desc != IORES_DESC_NONE);
> +}
> +
> +/*
> + * This function returns true if the target memory is marked as
> + * IORESOURCE_MEM and IORESOURCE_BUSY and described as other than
> + * IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
> + */
> +static bool __ioremap_check_if_mem(resource_size_t addr, unsigned long size)
> +{
> + u64 start, end;
> +
> + start = (u64)addr;
> + end = start + size - 1;
> +
> + return (walk_mem_res(start, end, NULL, __ioremap_res_desc_other) == 1);
> +}
> +
> /*
> * Remap an arbitrary physical address space into the kernel virtual
> * address space. It transparently creates kernel huge I/O mapping when
> @@ -146,7 +166,15 @@ 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() && __ioremap_check_if_mem(phys_addr, size))
> + prot = pgprot_encrypted(prot);
Hmm, so this function already does walk_system_ram_range() a bit
earlier and now on SEV systems we're going to do it again. Can we make
walk_system_ram_range() return a distinct value for SEV systems and act
accordingly in __ioremap_caller() instead of repeating the operation?
It looks to me like we could...
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284
(AG Nürnberg)
--
[RFC Part1 PATCH v3 11/17] x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages
From: Tom Lendacky
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
Signed-off-by: Brijesh Singh
---
arch/x86/mm/ioremap.c | 28
include/linux/ioport.h | 3 +++
kernel/resource.c | 17 +
3 files changed, 48 insertions(+)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index c0be7cf..7b27332 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -69,6 +69,26 @@ static int __ioremap_check_ram(unsigned long start_pfn,
unsigned long nr_pages,
return 0;
}
+static int __ioremap_res_desc_other(struct resource *res, void *arg)
+{
+ return (res->desc != IORES_DESC_NONE);
+}
+
+/*
+ * This function returns true if the target memory is marked as
+ * IORESOURCE_MEM and IORESOURCE_BUSY and described as other than
+ * IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
+ */
+static bool __ioremap_check_if_mem(resource_size_t addr, unsigned long size)
+{
+ u64 start, end;
+
+ start = (u64)addr;
+ end = start + size - 1;
+
+ return (walk_mem_res(start, end, NULL, __ioremap_res_desc_other) == 1);
+}
+
/*
* Remap an arbitrary physical address space into the kernel virtual
* address space. It transparently creates kernel huge I/O mapping when
@@ -146,7 +166,15 @@ 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() && __ioremap_check_if_mem(phys_addr, size))
+ prot = pgprot_encrypted(prot);
+
switch (pcm) {
case _PAGE_CACHE_MODE_UC:
default:
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 1c66b9c..297f5b8 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -268,6 +268,9 @@ extern int
walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
void *arg, int (*func)(unsigned long, unsigned long, void *));
extern int
+walk_mem_res(u64 start, u64 end, void *arg,
+int (*func)(struct resource *, void *));
+extern int
walk_system_ram_res(u64 start, u64 end, void *arg,
int (*func)(struct resource *, void *));
extern int
diff --git a/kernel/resource.c b/kernel/resource.c
index 5f9ee7bb0..ec3fa0c 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -468,6 +468,23 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
arg, func);
}
+/*
+ * This function calls the @func callback against all memory ranges, which
+ * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.
+ */
+int walk_mem_res(u64 start, u64 end, void *arg,
+int (*func)(struct resource *, void *))
+{
+ struct resource res;
+
+ res.start = start;
+ res.end = end;
+ res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+
+ return __walk_iomem_res_desc(&res, IORES_DESC_NONE, true,
+arg, func);
+}
+
#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
/*
--
2.9.4
