[RFC,52/62] x86/mm: introduce common code for mem encryption

Commit Message

[e-mail] May 8, 2019, 2:44 p.m. UTC

From: Jacob Pan <[e-mail]>

Both Intel MKTME and AMD SME have needs to support DMA address
translation with encryption related bits. Common functions are
introduced in this patch to keep DMA generic code abstracted.

Signed-off-by: Jacob Pan <[e-mail]>
Signed-off-by: Kirill A. Shutemov <[e-mail]>
---
 arch/x86/Kconfig                 |  4 ++++
 arch/x86/mm/Makefile             |  1 +
 arch/x86/mm/mem_encrypt_common.c | 28 ++++++++++++++++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 arch/x86/mm/mem_encrypt_common.c

Comments

Christoph Hellwig May 8, 2019, 4:58 p.m. UTC | #1

On Wed, May 08, 2019 at 05:44:12PM +0300, Kirill A. Shutemov wrote:
> +EXPORT_SYMBOL_GPL(__mem_encrypt_dma_set);
> +
> +phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
> +{
> +	if (sme_active())
> +		return __sme_clr(paddr);
> +
> +	return paddr & ~mktme_keyid_mask;
> +}
> +EXPORT_SYMBOL_GPL(__mem_encrypt_dma_clear);

In general nothing related to low-level dma address should ever
be exposed to modules.  What is your intended user for these two?

Jacob Pan May 8, 2019, 8:52 p.m. UTC | #2

On Wed, 8 May 2019 09:58:30 -0700
Christoph Hellwig <[e-mail]> wrote:

> On Wed, May 08, 2019 at 05:44:12PM +0300, Kirill A. Shutemov wrote:
> > +EXPORT_SYMBOL_GPL(__mem_encrypt_dma_set);
> > +
> > +phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
> > +{
> > +	if (sme_active())
> > +		return __sme_clr(paddr);
> > +
> > +	return paddr & ~mktme_keyid_mask;
> > +}
> > +EXPORT_SYMBOL_GPL(__mem_encrypt_dma_clear);  
> 
> In general nothing related to low-level dma address should ever
> be exposed to modules.  What is your intended user for these two?

Right no need to export. It will be used by IOMMU drivers.

[e-mail] May 8, 2019, 9:21 p.m. UTC | #3

On Wed, May 08, 2019 at 08:52:25PM +0000, Jacob Pan wrote:
> On Wed, 8 May 2019 09:58:30 -0700
> Christoph Hellwig <[e-mail]> wrote:
> 
> > On Wed, May 08, 2019 at 05:44:12PM +0300, Kirill A. Shutemov wrote:
> > > +EXPORT_SYMBOL_GPL(__mem_encrypt_dma_set);
> > > +
> > > +phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
> > > +{
> > > +	if (sme_active())
> > > +		return __sme_clr(paddr);
> > > +
> > > +	return paddr & ~mktme_keyid_mask;
> > > +}
> > > +EXPORT_SYMBOL_GPL(__mem_encrypt_dma_clear);  
> > 
> > In general nothing related to low-level dma address should ever
> > be exposed to modules.  What is your intended user for these two?
> 
> Right no need to export. It will be used by IOMMU drivers.

I will drop these EXPORT_SYMBOL_GPL().

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 62cfb381fee3..ce9642e2c31b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1505,11 +1505,15 @@  config X86_CPA_STATISTICS
 config ARCH_HAS_MEM_ENCRYPT
 	def_bool y
 
+config X86_MEM_ENCRYPT_COMMON
+	def_bool n
+
 config AMD_MEM_ENCRYPT
 	bool "AMD Secure Memory Encryption (SME) support"
 	depends on X86_64 && CPU_SUP_AMD
 	select DYNAMIC_PHYSICAL_MASK
 	select ARCH_USE_MEMREMAP_PROT
+	select X86_MEM_ENCRYPT_COMMON
 	---help---
 	  Say yes to enable support for the encryption of system memory.
 	  This requires an AMD processor that supports Secure Memory
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 4ebee899c363..89dddbc01b1b 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -55,3 +55,4 @@  obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_identity.o
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_boot.o
 
 obj-$(CONFIG_X86_INTEL_MKTME)	+= mktme.o
+obj-$(CONFIG_X86_MEM_ENCRYPT_COMMON)	+= mem_encrypt_common.o
diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
new file mode 100644
index 000000000000..2adee65eec46
--- /dev/null
+++ b/arch/x86/mm/mem_encrypt_common.c
@@ -0,0 +1,28 @@ 
+#include <linux/mm.h>
+#include <linux/mem_encrypt.h>
+#include <asm/mktme.h>
+
+/*
+ * Encryption bits need to be set and cleared for both Intel MKTME and
+ * AMD SME when converting between DMA address and physical address.
+ */
+dma_addr_t __mem_encrypt_dma_set(dma_addr_t daddr, phys_addr_t paddr)
+{
+	unsigned long keyid;
+
+	if (sme_active())
+		return __sme_set(daddr);
+	keyid = page_keyid(pfn_to_page(__phys_to_pfn(paddr)));
+
+	return (daddr & ~mktme_keyid_mask) | (keyid << mktme_keyid_shift);
+}
+EXPORT_SYMBOL_GPL(__mem_encrypt_dma_set);
+
+phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
+{
+	if (sme_active())
+		return __sme_clr(paddr);
+
+	return paddr & ~mktme_keyid_mask;
+}
+EXPORT_SYMBOL_GPL(__mem_encrypt_dma_clear);