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From: Kai Huang <kai.huang@intel.com>
To: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org
Cc: seanjc@google.com, jarkko@kernel.org, luto@kernel.org,
	dave.hansen@intel.com, haitao.huang@intel.com,
	pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de,
	mingo@redhat.com, hpa@zytor.com, jethro@fortanix.com,
	b.thiel@posteo.de, Kai Huang <kai.huang@intel.com>
Subject: [RFC PATCH v2 06/26] x86/cpu/intel: Allow SGX virtualization without Launch Control support
Date: Mon, 18 Jan 2021 16:27:19 +1300	[thread overview]
Message-ID: <a6c0b0d2632a6c603e68d9bdc81f564290ff04ad.1610935432.git.kai.huang@intel.com> (raw)
In-Reply-To: <cover.1610935432.git.kai.huang@intel.com>

From: Sean Christopherson <sean.j.christopherson@intel.com>

The kernel will currently disable all SGX support if the hardware does
not support launch control.  Make it more permissive to allow SGX
virtualization on systems without Launch Control support.  This will
allow KVM to expose SGX to guests that have less-strict requirements on
the availability of flexible launch control.

Improve error message to distinguish between three cases.  There are two
cases where SGX support is completely disabled:
1) SGX has been disabled completely by the BIOS
2) SGX LC is locked by the BIOS.  Bare-metal support is disabled because
   of LC unavailability.  SGX virtualization is unavailable (because of
   Kconfig).
One where it is partially available:
3) SGX LC is locked by the BIOS.  Bare-metal support is disabled because
   of LC unavailability.  SGX virtualization is supported.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Co-developed-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
v1->v2:

 - Refined commit message per Dave's comments.
 - Added check to only enable SGX virtualization when VMX is supported, per
   Dave's comment.
 - Refined error msg print to explicitly call out SGX virtualization will be
   supported when LC is locked by BIOS, per Dave's comment.
---
 arch/x86/kernel/cpu/feat_ctl.c | 64 +++++++++++++++++++++++++++-------
 1 file changed, 51 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
index 7937a315f8cf..7bd8c57c62fa 100644
--- a/arch/x86/kernel/cpu/feat_ctl.c
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -98,6 +98,11 @@ static void clear_sgx_caps(void)
 	setup_clear_cpu_cap(X86_FEATURE_SGX);
 }
 
+static void clear_sgx_lc(void)
+{
+	setup_clear_cpu_cap(X86_FEATURE_SGX_LC);
+}
+
 static int __init nosgx(char *str)
 {
 	clear_sgx_caps();
@@ -110,7 +115,7 @@ early_param("nosgx", nosgx);
 void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
 {
 	bool tboot = tboot_enabled();
-	bool enable_sgx;
+	bool enable_vmx, enable_sgx_virt, enable_sgx_driver;
 	u64 msr;
 
 	if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
@@ -119,13 +124,24 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
 		return;
 	}
 
+	enable_vmx = cpu_has(c, X86_FEATURE_VMX) &&
+		     IS_ENABLED(CONFIG_KVM_INTEL);
+
 	/*
-	 * Enable SGX if and only if the kernel supports SGX and Launch Control
-	 * is supported, i.e. disable SGX if the LE hash MSRs can't be written.
+	 * Enable SGX if and only if the kernel supports SGX.  Require Launch
+	 * Control support if SGX virtualization is *not* supported, i.e.
+	 * disable SGX if the LE hash MSRs can't be written and SGX can't be
+	 * exposed to a KVM guest (which might support non-LC configurations).
 	 */
-	enable_sgx = cpu_has(c, X86_FEATURE_SGX) &&
-		     cpu_has(c, X86_FEATURE_SGX_LC) &&
-		     IS_ENABLED(CONFIG_X86_SGX);
+	enable_sgx_driver = cpu_has(c, X86_FEATURE_SGX) &&
+			    cpu_has(c, X86_FEATURE_SGX1) &&
+			    IS_ENABLED(CONFIG_X86_SGX) &&
+			    cpu_has(c, X86_FEATURE_SGX_LC);
+	enable_sgx_virt = cpu_has(c, X86_FEATURE_SGX) &&
+			  cpu_has(c, X86_FEATURE_SGX1) &&
+			  IS_ENABLED(CONFIG_X86_SGX) &&
+			  IS_ENABLED(CONFIG_X86_SGX_VIRTUALIZATION) &&
+			  enable_vmx;
 
 	if (msr & FEAT_CTL_LOCKED)
 		goto update_caps;
@@ -141,15 +157,18 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
 	 * i.e. KVM is enabled, to avoid unnecessarily adding an attack vector
 	 * for the kernel, e.g. using VMX to hide malicious code.
 	 */
-	if (cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL)) {
+	if (enable_vmx) {
 		msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
 
 		if (tboot)
 			msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX;
 	}
 
-	if (enable_sgx)
-		msr |= FEAT_CTL_SGX_ENABLED | FEAT_CTL_SGX_LC_ENABLED;
+	if (enable_sgx_driver || enable_sgx_virt) {
+		msr |= FEAT_CTL_SGX_ENABLED;
+		if (enable_sgx_driver)
+			msr |= FEAT_CTL_SGX_LC_ENABLED;
+	}
 
 	wrmsrl(MSR_IA32_FEAT_CTL, msr);
 
@@ -172,10 +191,29 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
 	}
 
 update_sgx:
-	if (!(msr & FEAT_CTL_SGX_ENABLED) ||
-	    !(msr & FEAT_CTL_SGX_LC_ENABLED) || !enable_sgx) {
-		if (enable_sgx)
-			pr_err_once("SGX disabled by BIOS\n");
+	if (!(msr & FEAT_CTL_SGX_ENABLED)) {
+		if (enable_sgx_driver || enable_sgx_virt)
+			pr_err_once("SGX disabled by BIOS.\n");
 		clear_sgx_caps();
+		return;
+	}
+
+	/*
+	 * VMX feature bit may be cleared due to being disabled in BIOS,
+	 * in which case SGX virtualization cannot be supported either.
+	 */
+	if (!cpu_has(c, X86_FEATURE_VMX) && enable_sgx_virt) {
+		pr_err_once("SGX virtualization disabled due to lack of VMX.\n");
+		enable_sgx_virt = 0;
+	}
+
+	if (!(msr & FEAT_CTL_SGX_LC_ENABLED) && enable_sgx_driver) {
+		if (!enable_sgx_virt) {
+			pr_err_once("SGX Launch Control is locked. Disable SGX.\n");
+			clear_sgx_caps();
+		} else {
+			pr_err_once("SGX Launch Control is locked. Support SGX virtualization only.\n");
+			clear_sgx_lc();
+		}
 	}
 }
-- 
2.29.2


  parent reply	other threads:[~2021-01-18  3:28 UTC|newest]

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-18  3:26 [RFC PATCH v2 00/26] KVM SGX virtualization support Kai Huang
2021-01-18  3:26 ` [RFC PATCH v2 01/26] x86/cpufeatures: Add SGX1 and SGX2 sub-features Kai Huang
2021-01-19 16:19   ` Borislav Petkov
2021-01-19 18:03     ` Sean Christopherson
2021-01-19 22:54       ` Kai Huang
2021-01-20 10:28       ` Borislav Petkov
2021-01-20 11:50   ` Jarkko Sakkinen
2021-01-20 23:23     ` Kai Huang
2021-01-21  1:01       ` Jarkko Sakkinen
2021-01-18  3:26 ` [RFC PATCH v2 02/26] x86/sgx: Remove a warn from sgx_free_epc_page() Kai Huang
2021-01-19  8:32   ` Jarkko Sakkinen
2021-01-20  0:42     ` Kai Huang
2021-01-18  3:26 ` [RFC PATCH v2 03/26] x86/sgx: Wipe out EREMOVE " Kai Huang
2021-01-18  3:26 ` [RFC PATCH v2 04/26] x86/sgx: Add SGX_CHILD_PRESENT hardware error code Kai Huang
2021-01-20 11:51   ` Jarkko Sakkinen
2021-01-18  3:26 ` [RFC PATCH v2 05/26] x86/sgx: Introduce virtual EPC for use by KVM guests Kai Huang
2021-01-20 11:54   ` Jarkko Sakkinen
2021-01-20 17:40     ` Sean Christopherson
2021-01-21  0:54       ` Jarkko Sakkinen
2021-01-21  0:55         ` Jarkko Sakkinen
2021-01-18  3:27 ` Kai Huang [this message]
2021-01-20 21:02   ` [RFC PATCH v2 06/26] x86/cpu/intel: Allow SGX virtualization without Launch Control support Dave Hansen
2021-01-20 22:36     ` Sean Christopherson
2021-01-20 23:27       ` Dave Hansen
2021-01-20 23:48         ` Kai Huang
2021-01-20 23:51           ` Dave Hansen
2021-01-21  1:53             ` Kai Huang
2021-01-21 14:35               ` Jarkko Sakkinen
2021-01-21  1:12         ` Jarkko Sakkinen
2021-01-20 23:50     ` Kai Huang
2021-01-21  1:11     ` Jarkko Sakkinen
2021-01-18  3:27 ` [RFC PATCH v2 07/26] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Kai Huang
2021-01-18  3:27 ` [RFC PATCH v2 08/26] x86/sgx: Expose SGX architectural definitions to the kernel Kai Huang
2021-01-20 11:58   ` Jarkko Sakkinen
2021-01-20 23:53     ` Kai Huang
2021-01-18  3:27 ` [RFC PATCH v2 09/26] x86/sgx: Move ENCLS leaf definitions to sgx_arch.h Kai Huang
2021-01-20 11:59   ` Jarkko Sakkinen
2021-01-18  3:28 ` [RFC PATCH v2 10/26] x86/sgx: Add SGX2 ENCLS leaf definitions (EAUG, EMODPR and EMODT) Kai Huang
2021-01-20 11:59   ` Jarkko Sakkinen
2021-01-18  3:28 ` [RFC PATCH v2 11/26] x86/sgx: Add encls_faulted() helper Kai Huang
2021-01-20 12:03   ` Jarkko Sakkinen
2021-01-20 23:43     ` Kai Huang
2021-01-21  1:08       ` Jarkko Sakkinen
2021-01-21  1:12         ` Kai Huang
2021-01-21 14:38           ` Jarkko Sakkinen
2021-01-18  3:28 ` [RFC PATCH v2 12/26] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs Kai Huang
2021-01-20 12:03   ` Jarkko Sakkinen
2021-01-20 18:36     ` Dave Hansen
2021-01-20 23:36       ` Kai Huang
2021-01-20 23:50         ` Dave Hansen
2021-01-21  1:06           ` Kai Huang
2021-01-21  1:15             ` Dave Hansen
2021-01-21  1:44               ` Kai Huang
2021-01-21 14:36                 ` Jarkko Sakkinen
2021-01-21  1:18             ` Kai Huang
2021-01-21  1:09         ` Jarkko Sakkinen
2021-01-21  1:08       ` Jarkko Sakkinen
2021-01-18  3:28 ` [RFC PATCH v2 13/26] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM Kai Huang
2021-01-20 12:04   ` Jarkko Sakkinen
2021-01-20 23:29     ` Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 14/26] x86/sgx: Move provisioning device creation out of SGX driver Kai Huang
2021-01-20 14:09   ` Jarkko Sakkinen
2021-01-20 23:24     ` Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 15/26] KVM: VMX: Convert vcpu_vmx.exit_reason to a union Kai Huang
2021-01-20 14:18   ` Jarkko Sakkinen
2021-01-20 16:39     ` Sean Christopherson
2021-01-21  0:47       ` Jarkko Sakkinen
2021-01-21 16:33         ` Sean Christopherson
2021-01-22 17:29           ` Jarkko Sakkinen
2021-01-18  3:28 ` [RFC PATCH v2 16/26] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-01-20 14:19   ` Jarkko Sakkinen
2021-01-18  3:28 ` [RFC PATCH v2 17/26] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 18/26] KVM: x86: Add support for reverse CPUID lookup of scattered features Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 19/26] KVM: x86: Add reverse-CPUID lookup support for scattered SGX features Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 20/26] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 21/26] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 22/26] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 23/26] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 24/26] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-01-18  3:28 ` [RFC PATCH v2 25/26] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-01-18  3:29 ` [RFC PATCH v2 26/26] KVM: x86: Add capability to grant VM access to privileged SGX attribute Kai Huang
2021-01-19  8:23 ` [RFC PATCH v2 00/26] KVM SGX virtualization support Jarkko Sakkinen
2021-01-20  0:52   ` Kai Huang
2021-01-20 16:35     ` Sean Christopherson
2021-01-20 16:39       ` Paolo Bonzini
2021-01-21  1:28         ` Kai Huang
2021-01-20 23:43     ` Jarkko Sakkinen
2021-01-20 23:52       ` Kai Huang
2021-01-21  1:16         ` Jarkko Sakkinen
2021-01-21  1:27           ` Kai Huang
2021-01-21 14:34             ` Jarkko Sakkinen

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