[RFC PATCH v4 12/26] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs

Kai Huang
2021-02-08T11:11:35Z

Add a helper to update SGX_LEPUBKEYHASHn MSRs. SGX virtualization also
needs to update those MSRs based on guest's "virtual" SGX_LEPUBKEYHASHn
before EINIT from guest.

Acked-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
v3->v4:
- Patch rebase due to sgx/virt.h was removed per Dave, and sgx_vepc_init()
declaration was moved to sgx/sgx.h.
- Added Jarkko's Ack-by. Restored Dave's Acked-by.

v2->v3:

- Added comment for sgx_update_lepubkeyhash(), per Jarkko and Dave.

---
arch/x86/kernel/cpu/sgx/ioctl.c | 5 ++---
arch/x86/kernel/cpu/sgx/main.c | 15 +++++++++++++++
arch/x86/kernel/cpu/sgx/sgx.h | 2 ++
3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index e5977752c7be..1bae754268d1 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -495,7 +495,7 @@ static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
void *token)
{
u64 mrsigner[4];
- int i, j, k;
+ int i, j;
void *addr;
int ret;

@@ -544,8 +544,7 @@ static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,

preempt_disable();

- for (k = 0; k < 4; k++)
- wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + k, mrsigner[k]);
+ sgx_update_lepubkeyhash(mrsigner);

ret = __einit(sigstruct, token, addr);

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 60a7a630212e..dadd7acac4ad 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -696,6 +696,21 @@ static bool __init sgx_page_cache_init(void)
return true;
}

+
+/*
+ * Update the SGX_LEPUBKEYHASH MSRs to the values specified by caller.
+ * Bare-metal driver requires to update them to hash of enclave's signer
+ * before EINIT. KVM needs to update them to guest's virtual MSR values
+ * before doing EINIT from guest.
+ */
+void sgx_update_lepubkeyhash(u64 *lepubkeyhash)
+{
+ int i;
+
+ for (i = 0; i < 4; i++)
+ wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
+}
+
static int __init sgx_init(void)
{
int ret;
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 161d2d8ac3b6..371fdf3b16a8 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -92,4 +92,6 @@ static inline int __init sgx_vepc_init(void)
}
#endif

+void sgx_update_lepubkeyhash(u64 *lepubkeyhash);
+
#endif /* _X86_SGX_H */
--
2.29.2