Re: [RFC Part1 PATCH v3 08/17] x86/efi: Access EFI data as encrypted when SEV is active

[Tom Lendacky]

On 7/28/2017 5:31 AM, Borislav Petkov wrote:

On Mon, Jul 24, 2017 at 02:07:48PM -0500, Brijesh Singh wrote:

From: Tom Lendacky 

EFI data is encrypted when the kernel is run under SEV. Update the
page table references to be sure the EFI memory areas are accessed
encrypted.

Signed-off-by: Tom Lendacky 
Signed-off-by: Brijesh Singh 
---
  arch/x86/platform/efi/efi_64.c | 15 ++-
  1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 12e8388..1ecb3f6 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -32,6 +32,7 @@
  #include 
  #include 
  #include 
+#include 
  
  #include 

  #include 
@@ -369,7 +370,10 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, 
unsigned num_pages)
 * as trim_bios_range() will reserve the first page and isolate it away
 * from memory allocators anyway.
 */
-   if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
+   pf = _PAGE_RW;
+   if (sev_active())
+   pf |= _PAGE_ENC;


\n here


+   if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, pf)) {
pr_err("Failed to create 1:1 mapping for the first page!\n");
return 1;
}
@@ -412,6 +416,9 @@ static void __init __map_region(efi_memory_desc_t *md, u64 
va)
if (!(md->attribute & EFI_MEMORY_WB))
flags |= _PAGE_PCD;
  
+	if (sev_active())

+   flags |= _PAGE_ENC;
+
pfn = md->phys_addr >> PAGE_SHIFT;
if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
@@ -511,6 +518,9 @@ static int __init efi_update_mappings(efi_memory_desc_t 
*md, unsigned long pf)
pgd_t *pgd = efi_pgd;
int err1, err2;
  
+	if (sev_active())

+   pf |= _PAGE_ENC;


Move this assignment to the caller efi_update_mem_attr() where pf is being
set...


Will do.




+
/* Update the 1:1 mapping */
pfn = md->phys_addr >> PAGE_SHIFT;
err1 = kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, 
pf);
@@ -589,6 +599,9 @@ void __init efi_runtime_update_mappings(void)
(md->type != EFI_RUNTIME_SERVICES_CODE))
pf |= _PAGE_RW;
  
+		if (sev_active())

+   pf |= _PAGE_ENC;


... just like here.


Yup.

Thanks,
Tom




+
efi_update_mappings(md, pf);


In general, I'm not totally excited about that sprinkling of if
(sev_active())... :-\


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Re: [RFC Part1 PATCH v3 08/17] x86/efi: Access EFI data as encrypted when SEV is active

[Borislav Petkov]

On Mon, Jul 24, 2017 at 02:07:48PM -0500, Brijesh Singh wrote:
> From: Tom Lendacky 
> 
> EFI data is encrypted when the kernel is run under SEV. Update the
> page table references to be sure the EFI memory areas are accessed
> encrypted.
> 
> Signed-off-by: Tom Lendacky 
> Signed-off-by: Brijesh Singh 
> ---
>  arch/x86/platform/efi/efi_64.c | 15 ++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
> index 12e8388..1ecb3f6 100644
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -32,6 +32,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  #include 
>  #include 
> @@ -369,7 +370,10 @@ int __init efi_setup_page_tables(unsigned long 
> pa_memmap, unsigned num_pages)
>* as trim_bios_range() will reserve the first page and isolate it away
>* from memory allocators anyway.
>*/
> - if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
> + pf = _PAGE_RW;
> + if (sev_active())
> + pf |= _PAGE_ENC;

\n here

> + if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, pf)) {
>   pr_err("Failed to create 1:1 mapping for the first page!\n");
>   return 1;
>   }
> @@ -412,6 +416,9 @@ static void __init __map_region(efi_memory_desc_t *md, 
> u64 va)
>   if (!(md->attribute & EFI_MEMORY_WB))
>   flags |= _PAGE_PCD;
>  
> + if (sev_active())
> + flags |= _PAGE_ENC;
> +
>   pfn = md->phys_addr >> PAGE_SHIFT;
>   if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
>   pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
> @@ -511,6 +518,9 @@ static int __init efi_update_mappings(efi_memory_desc_t 
> *md, unsigned long pf)
>   pgd_t *pgd = efi_pgd;
>   int err1, err2;
>  
> + if (sev_active())
> + pf |= _PAGE_ENC;

Move this assignment to the caller efi_update_mem_attr() where pf is being
set...

> +
>   /* Update the 1:1 mapping */
>   pfn = md->phys_addr >> PAGE_SHIFT;
>   err1 = kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, 
> pf);
> @@ -589,6 +599,9 @@ void __init efi_runtime_update_mappings(void)
>   (md->type != EFI_RUNTIME_SERVICES_CODE))
>   pf |= _PAGE_RW;
>  
> + if (sev_active())
> + pf |= _PAGE_ENC;

... just like here.

> +
>   efi_update_mappings(md, pf);

In general, I'm not totally excited about that sprinkling of if
(sev_active())... :-\

-- 
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 
(AG Nürnberg)
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[RFC Part1 PATCH v3 08/17] x86/efi: Access EFI data as encrypted when SEV is active

[Brijesh Singh]

From: Tom Lendacky 

EFI data is encrypted when the kernel is run under SEV. Update the
page table references to be sure the EFI memory areas are accessed
encrypted.

Signed-off-by: Tom Lendacky 
Signed-off-by: Brijesh Singh 
---
 arch/x86/platform/efi/efi_64.c | 15 ++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 12e8388..1ecb3f6 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -32,6 +32,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -369,7 +370,10 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, 
unsigned num_pages)
 * as trim_bios_range() will reserve the first page and isolate it away
 * from memory allocators anyway.
 */
-   if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
+   pf = _PAGE_RW;
+   if (sev_active())
+   pf |= _PAGE_ENC;
+   if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, pf)) {
pr_err("Failed to create 1:1 mapping for the first page!\n");
return 1;
}
@@ -412,6 +416,9 @@ static void __init __map_region(efi_memory_desc_t *md, u64 
va)
if (!(md->attribute & EFI_MEMORY_WB))
flags |= _PAGE_PCD;
 
+   if (sev_active())
+   flags |= _PAGE_ENC;
+
pfn = md->phys_addr >> PAGE_SHIFT;
if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
@@ -511,6 +518,9 @@ static int __init efi_update_mappings(efi_memory_desc_t 
*md, unsigned long pf)
pgd_t *pgd = efi_pgd;
int err1, err2;
 
+   if (sev_active())
+   pf |= _PAGE_ENC;
+
/* Update the 1:1 mapping */
pfn = md->phys_addr >> PAGE_SHIFT;
err1 = kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, 
pf);
@@ -589,6 +599,9 @@ void __init efi_runtime_update_mappings(void)
(md->type != EFI_RUNTIME_SERVICES_CODE))
pf |= _PAGE_RW;
 
+   if (sev_active())
+   pf |= _PAGE_ENC;
+
efi_update_mappings(md, pf);
}
 }
-- 
2.9.4

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