On Mon, Aug 22, 2016 at 05:37:49PM -0500, Tom Lendacky wrote:
> This patch adds support to be change the memory encryption attribute for
> one or more memory pages.
>
> 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 | 75 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 134 insertions(+)
...
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 72c292d..0ba9382 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -1728,6 +1728,81 @@ 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;
> +
> + if (*cpa->vaddr & ~PAGE_MASK) {
> + *cpa->vaddr &= PAGE_MASK;
> +
> + /* People should not be passing in unaligned addresses */
> + WARN_ON_ONCE(1);
Let's make this more user-friendly:
if (WARN_ONCE(*cpa->vaddr & ~PAGE_MASK, "Misaligned address: 0x%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;
> +
> + /*
> + * 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);
So if we fail (ret != 0) we do WBINVD unconditionally even if we don't
have to?
Don't you want this instead:
ret = __change_page_attr_set_clr(cpa, 1);
if (ret)
goto out;
/* Check whether we really changed something */
if (!(cpa->flags & CPA_FLUSHTLB))
goto out;
/*
* On success we use CLFLUSH, when the CPU supports it to
* avoid the WBINVD.
*/
if (static_cpu_has(X86_FEATURE_CLFLUSH))
cpa_flush_range(addr, numpages, 1);
else
cpa_flush_all(1);
out:
return ret;
}
?
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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