On 11/17/2016 11:39 AM, Borislav Petkov wrote:

On Wed, Nov 09, 2016 at 06:36:55PM -0600, Tom Lendacky wrote:

quoted

This patch adds support to be change the memory encryption attribute for
one or more memory pages.

"Add support for changing ..."

Yeah, I kind of messed up that description a bit!

quoted

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/include/asm/cacheflush.h  |    3 +
 arch/x86/include/asm/mem_encrypt.h |   13 ++++++
 arch/x86/mm/mem_encrypt.c          |   43 +++++++++++++++++++++
 arch/x86/mm/pageattr.c             |   73 ++++++++++++++++++++++++++++++++++++
 4 files changed, 132 insertions(+)

...

quoted

diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 411210d..41cfdf9 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c

@@ -18,6 +18,7 @@
 #include <asm/fixmap.h>
 #include <asm/setup.h>
 #include <asm/bootparam.h>
+#include <asm/cacheflush.h>
 
 extern pmdval_t early_pmd_flags;
 int __init __early_make_pgtable(unsigned long, pmdval_t);

@@ -33,6 +34,48 @@ EXPORT_SYMBOL_GPL(sme_me_mask);
 /* Buffer used for early in-place encryption by BSP, no locking needed */
 static char sme_early_buffer[PAGE_SIZE] __aligned(PAGE_SIZE);
 
+int sme_set_mem_enc(void *vaddr, unsigned long size)
+{
+	unsigned long addr, numpages;
+
+	if (!sme_me_mask)
+		return 0;

So those interfaces look duplicated to me: you have exported
sme_set_mem_enc/sme_set_mem_unenc which take @size and then you have
set_memory_enc/set_memory_dec which take numpages.

And then you're testing sme_me_mask in both.

What I'd prefer to have is only *two* set_memory_enc/set_memory_dec
which take size in bytes and one workhorse __set_memory_enc_dec() which
does it all. The user shouldn't have to care about numpages or size or
whatever.

Ok?

Yup, makes sense. I'll redo this.

quoted

+
+	addr = (unsigned long)vaddr & PAGE_MASK;
+	numpages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+	/*
+	 * The set_memory_xxx functions take an integer for numpages, make
+	 * sure it doesn't exceed that.
+	 */
+	if (numpages > INT_MAX)
+		return -EINVAL;
+
+	return set_memory_enc(addr, numpages);
+}
+EXPORT_SYMBOL_GPL(sme_set_mem_enc);
+
+int sme_set_mem_unenc(void *vaddr, unsigned long size)
+{
+	unsigned long addr, numpages;
+
+	if (!sme_me_mask)
+		return 0;
+
+	addr = (unsigned long)vaddr & PAGE_MASK;
+	numpages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+	/*
+	 * The set_memory_xxx functions take an integer for numpages, make
+	 * sure it doesn't exceed that.
+	 */
+	if (numpages > INT_MAX)
+		return -EINVAL;
+
+	return set_memory_dec(addr, numpages);
+}
+EXPORT_SYMBOL_GPL(sme_set_mem_unenc);
+
 /*
  * This routine does not change the underlying encryption setting of the
  * page(s) that map this memory. It assumes that eventually the memory is

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index b8e6bb5..babf3a6 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c

@@ -1729,6 +1729,79 @@ int set_memory_4k(unsigned long addr, int numpages)
 					__pgprot(0), 1, 0, NULL);
 }
 
+static int __set_memory_enc_dec(struct cpa_data *cpa)
+{
+	unsigned long addr;
+	int numpages;
+	int ret;
+
+	/* People should not be passing in unaligned addresses */
+	if (WARN_ONCE(*cpa->vaddr & ~PAGE_MASK,
+		      "misaligned address: %#lx\n", *cpa->vaddr))
+		*cpa->vaddr &= PAGE_MASK;
+
+	addr = *cpa->vaddr;
+	numpages = cpa->numpages;
+
+	/* Must avoid aliasing mappings in the highmem code */
+	kmap_flush_unused();
+	vm_unmap_aliases();
+
+	ret = __change_page_attr_set_clr(cpa, 1);
+
+	/* Check whether we really changed something */
+	if (!(cpa->flags & CPA_FLUSHTLB))
+		goto out;

That label is used only once - just "return ret;" here.

Yup, will do.

quoted

+	/*
+	 * On success we use CLFLUSH, when the CPU supports it to
+	 * avoid the WBINVD.
+	 */
+	if (!ret && static_cpu_has(X86_FEATURE_CLFLUSH))
+		cpa_flush_range(addr, numpages, 1);
+	else
+		cpa_flush_all(1);
+
+out:
+	return ret;
+}
+
+int set_memory_enc(unsigned long addr, int numpages)
+{
+	struct cpa_data cpa;
+
+	if (!sme_me_mask)
+		return 0;
+
+	memset(&cpa, 0, sizeof(cpa));
+	cpa.vaddr = &addr;
+	cpa.numpages = numpages;
+	cpa.mask_set = __pgprot(_PAGE_ENC);
+	cpa.mask_clr = __pgprot(0);
+	cpa.pgd = init_mm.pgd;

You could move that...

quoted

+
+	return __set_memory_enc_dec(&cpa);
+}
+EXPORT_SYMBOL(set_memory_enc);
+
+int set_memory_dec(unsigned long addr, int numpages)
+{
+	struct cpa_data cpa;
+
+	if (!sme_me_mask)
+		return 0;
+
+	memset(&cpa, 0, sizeof(cpa));
+	cpa.vaddr = &addr;
+	cpa.numpages = numpages;
+	cpa.mask_set = __pgprot(0);
+	cpa.mask_clr = __pgprot(_PAGE_ENC);
+	cpa.pgd = init_mm.pgd;

... and that into __set_memory_enc_dec() too and pass in a "bool dec" or
"bool enc" or so which presets mask_set and mask_clr properly.

See above. I think two functions exported to other in-kernel users are
more than enough.

Should I move this functionality into the sme_set_mem_* functions or
remove the sme_set_mem_* functions and use the set_memory_* functions
directly.  The latter means calculating the number of pages, but makes
it clear that this works on a page level while the former keeps
everything the mem_encrypt.c file (and I can change that to take in a
page count so that it is clear about the page boundary usage).

Thanks,
Tom

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