On 11/17/2016 11:39 AM, Borislav Petkov wrote:
> On Wed, Nov 09, 2016 at 06:36:55PM -0600, Tom Lendacky wrote:
>> 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!
>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
>> ---
>> 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(+)
>
> ...
>
>> 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.
>
>> +
>> + 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.
>
>> + /*
>> + * 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...
>
>> +
>> + 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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