From: Jarkko Sakkinen <jarkko@kernel.org>
To: linux-sgx@vger.kernel.org
Cc: Jarkko Sakkinen <jarkko@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] x86/sgx: Add SGX_PAGE_REPEAT flag for SGX_IOC_ENCLAVE_ADD_PAGES
Date: Thu, 10 Jun 2021 10:21:17 +0300 [thread overview]
Message-ID: <20210610072117.76987-1-jarkko@kernel.org> (raw)
For uninitialized data, there's a need to add the same page multiple times,
e.g. a zero page, instead of traversing the source memory forward. With the
current API, this requires to call SGX_IOC_ENCLAVE_ADD_PAGES multiple
times, once per page, which is not very efficient.
Add a new SGX_PAGE_REPEAT flag to resolve the issue. When this flag is set
to the 'flags' field of struct sgx_enclave_pages, the ioctl will apply the
page at 'src' multiple times, instead of moving forward in the address
space.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
arch/x86/include/uapi/asm/sgx.h | 3 +++
arch/x86/kernel/cpu/sgx/ioctl.c | 9 +++++++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
index 9690d6899ad9..d20fd54fa250 100644
--- a/arch/x86/include/uapi/asm/sgx.h
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -12,9 +12,12 @@
* enum sgx_page_flags - page control flags
* %SGX_PAGE_MEASURE: Measure the page contents with a sequence of
* ENCLS[EEXTEND] operations.
+ * %SGX_PAGE_REPEAT: Read the same page at 'src' multiple times,
+ * instead of traversing the memory forward.
*/
enum sgx_page_flags {
SGX_PAGE_MEASURE = 0x01,
+ SGX_PAGE_REPEAT = 0x02,
};
#define SGX_MAGIC 0xA4
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 83df20e3e633..d81bb257bad0 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -415,6 +415,7 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
{
struct sgx_enclave_add_pages add_arg;
struct sgx_secinfo secinfo;
+ unsigned long src;
unsigned long c;
int ret;
@@ -453,8 +454,12 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
if (need_resched())
cond_resched();
- ret = sgx_encl_add_page(encl, add_arg.src + c, add_arg.offset + c,
- &secinfo, add_arg.flags);
+ if (add_arg.flags & SGX_PAGE_REPEAT)
+ src = add_arg.src;
+ else
+ src = add_arg.src + c;
+
+ ret = sgx_encl_add_page(encl, src, add_arg.offset + c, &secinfo, add_arg.flags);
if (ret)
break;
}
--
2.31.1
next reply other threads:[~2021-06-10 7:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 7:21 Jarkko Sakkinen [this message]
2021-06-10 9:01 ` [PATCH] x86/sgx: Add SGX_PAGE_REPEAT flag for SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2021-06-10 14:11 ` Dave Hansen
2021-06-14 20:48 ` Jarkko Sakkinen
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