2020-07-16 13:54:33

by Jarkko Sakkinen

[permalink] [raw]
Subject: [PATCH v36 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control hardware bits

From: Sean Christopherson <[email protected]>

Add X86_FEATURE_SGX_LC, which informs whether or not the CPU supports SGX
Launch Control.

Add MSR_IA32_SGXLEPUBKEYHASH{0, 1, 2, 3}, which when combined contain a
SHA256 hash of a 3072-bit RSA public key. SGX backed software packages, so
called enclaves, are always signed. All enclaves signed with the public key
are unconditionally allowed to initialize. [1]

Add FEAT_CTL_SGX_LC_ENABLED, which informs whether the aformentioned MSRs
are writable or not. If the bit is off, the public key MSRs are read-only
for the OS.

If the MSRs are read-only, the platform must provide a launch enclave (LE).
LE can create cryptographic tokens for other enclaves that they can pass
together with their signature to the ENCLS(EINIT) opcode, which is used
to initialize enclaves.

Linux is unlikely to support the locked configuration because it takes away
the control of the launch decisions from the kernel.

[1] Intel SDM: 38.1.4 Intel SGX Launch Control Configuration

Reviewed-by: Borislav Petkov <[email protected]>
Acked-by: Jethro Beekman <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Co-developed-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/msr-index.h | 7 +++++++
2 files changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 545ac3e0e269..0a4541e4f076 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -352,6 +352,7 @@
#define X86_FEATURE_CLDEMOTE (16*32+25) /* CLDEMOTE instruction */
#define X86_FEATURE_MOVDIRI (16*32+27) /* MOVDIRI instruction */
#define X86_FEATURE_MOVDIR64B (16*32+28) /* MOVDIR64B instruction */
+#define X86_FEATURE_SGX_LC (16*32+30) /* Software Guard Extensions Launch Control */

/* AMD-defined CPU features, CPUID level 0x80000007 (EBX), word 17 */
#define X86_FEATURE_OVERFLOW_RECOV (17*32+ 0) /* MCA overflow recovery support */
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 18e08da19f16..3d7c89a8533f 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -582,6 +582,7 @@
#define FEAT_CTL_LOCKED BIT(0)
#define FEAT_CTL_VMX_ENABLED_INSIDE_SMX BIT(1)
#define FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX BIT(2)
+#define FEAT_CTL_SGX_LC_ENABLED BIT(17)
#define FEAT_CTL_SGX_ENABLED BIT(18)
#define FEAT_CTL_LMCE_ENABLED BIT(20)

@@ -602,6 +603,12 @@
#define MSR_IA32_UCODE_WRITE 0x00000079
#define MSR_IA32_UCODE_REV 0x0000008b

+/* Intel SGX Launch Enclave Public Key Hash MSRs */
+#define MSR_IA32_SGXLEPUBKEYHASH0 0x0000008C
+#define MSR_IA32_SGXLEPUBKEYHASH1 0x0000008D
+#define MSR_IA32_SGXLEPUBKEYHASH2 0x0000008E
+#define MSR_IA32_SGXLEPUBKEYHASH3 0x0000008F
+
#define MSR_IA32_SMM_MONITOR_CTL 0x0000009b
#define MSR_IA32_SMBASE 0x0000009e

--
2.25.1


2020-08-06 17:22:01

by Darren Kenny

[permalink] [raw]
Subject: Re: [PATCH v36 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control hardware bits

On Thursday, 2020-07-16 at 16:52:41 +03, Jarkko Sakkinen wrote:
> From: Sean Christopherson <[email protected]>
>
> Add X86_FEATURE_SGX_LC, which informs whether or not the CPU supports SGX
> Launch Control.
>
> Add MSR_IA32_SGXLEPUBKEYHASH{0, 1, 2, 3}, which when combined contain a
> SHA256 hash of a 3072-bit RSA public key. SGX backed software packages, so
> called enclaves, are always signed. All enclaves signed with the public key
> are unconditionally allowed to initialize. [1]
>
> Add FEAT_CTL_SGX_LC_ENABLED, which informs whether the aformentioned MSRs
> are writable or not. If the bit is off, the public key MSRs are read-only
> for the OS.
>
> If the MSRs are read-only, the platform must provide a launch enclave (LE).
> LE can create cryptographic tokens for other enclaves that they can pass
> together with their signature to the ENCLS(EINIT) opcode, which is used
> to initialize enclaves.
>
> Linux is unlikely to support the locked configuration because it takes away
> the control of the launch decisions from the kernel.
>
> [1] Intel SDM: 38.1.4 Intel SGX Launch Control Configuration
>
> Reviewed-by: Borislav Petkov <[email protected]>
> Acked-by: Jethro Beekman <[email protected]>
> Signed-off-by: Sean Christopherson <[email protected]>
> Co-developed-by: Jarkko Sakkinen <[email protected]>
> Signed-off-by: Jarkko Sakkinen <[email protected]>

Reviewed-by: Darren Kenny <[email protected]>

> ---
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/include/asm/msr-index.h | 7 +++++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index 545ac3e0e269..0a4541e4f076 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -352,6 +352,7 @@
> #define X86_FEATURE_CLDEMOTE (16*32+25) /* CLDEMOTE instruction */
> #define X86_FEATURE_MOVDIRI (16*32+27) /* MOVDIRI instruction */
> #define X86_FEATURE_MOVDIR64B (16*32+28) /* MOVDIR64B instruction */
> +#define X86_FEATURE_SGX_LC (16*32+30) /* Software Guard Extensions Launch Control */
>
> /* AMD-defined CPU features, CPUID level 0x80000007 (EBX), word 17 */
> #define X86_FEATURE_OVERFLOW_RECOV (17*32+ 0) /* MCA overflow recovery support */
> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> index 18e08da19f16..3d7c89a8533f 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -582,6 +582,7 @@
> #define FEAT_CTL_LOCKED BIT(0)
> #define FEAT_CTL_VMX_ENABLED_INSIDE_SMX BIT(1)
> #define FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX BIT(2)
> +#define FEAT_CTL_SGX_LC_ENABLED BIT(17)
> #define FEAT_CTL_SGX_ENABLED BIT(18)
> #define FEAT_CTL_LMCE_ENABLED BIT(20)
>
> @@ -602,6 +603,12 @@
> #define MSR_IA32_UCODE_WRITE 0x00000079
> #define MSR_IA32_UCODE_REV 0x0000008b
>
> +/* Intel SGX Launch Enclave Public Key Hash MSRs */
> +#define MSR_IA32_SGXLEPUBKEYHASH0 0x0000008C
> +#define MSR_IA32_SGXLEPUBKEYHASH1 0x0000008D
> +#define MSR_IA32_SGXLEPUBKEYHASH2 0x0000008E
> +#define MSR_IA32_SGXLEPUBKEYHASH3 0x0000008F
> +
> #define MSR_IA32_SMM_MONITOR_CTL 0x0000009b
> #define MSR_IA32_SMBASE 0x0000009e
>
> --
> 2.25.1