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From: Kai Huang <kai.huang@intel.com>
To: kvm@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, seanjc@google.com,
	jarkko@kernel.org, luto@kernel.org, dave.hansen@intel.com,
	rick.p.edgecombe@intel.com, haitao.huang@intel.com,
	pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de,
	mingo@redhat.com, hpa@zytor.com, jmattson@google.com,
	joro@8bytes.org, vkuznets@redhat.com, wanpengli@tencent.com,
	Kai Huang <kai.huang@intel.com>
Subject: [PATCH v2 17/25] KVM: x86: Add support for reverse CPUID lookup of scattered features
Date: Tue,  9 Mar 2021 14:40:24 +1300	[thread overview]
Message-ID: <d60975017c19af49c30487ea2b40ace1e7c7dfee.1615250634.git.kai.huang@intel.com> (raw)
In-Reply-To: <cover.1615250634.git.kai.huang@intel.com>

From: Sean Christopherson <seanjc@google.com>

Introduce a scheme that allows KVM's CPUID magic to support features
that are scattered in the kernel's feature words.  To advertise and/or
query guest support for CPUID-based features, KVM requires the bit
number of an X86_FEATURE_* to match the bit number in its associated
CPUID entry.  For scattered features, this does not hold true.

Add a framework to allow defining KVM-only words, stored in
kvm_cpu_caps after the shared kernel caps, that can be used to gather
the scattered feature bits by translating X86_FEATURE_* flags into their
KVM-defined feature.

Note, because reverse_cpuid_check() effectively forces kvm_cpu_caps
lookups to be resolved at compile time, there is no runtime cost for
translating from kernel-defined to kvm-defined features.

More details here:  https://lkml.kernel.org/r/X/jxCOLG+HUO4QlZ@google.com

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
 arch/x86/kvm/cpuid.c | 32 +++++++++++++++++++++++++++-----
 arch/x86/kvm/cpuid.h | 39 ++++++++++++++++++++++++++++++++++-----
 2 files changed, 61 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 6bd2f8b830e4..a0e7be9ed449 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -28,7 +28,7 @@
  * Unlike "struct cpuinfo_x86.x86_capability", kvm_cpu_caps doesn't need to be
  * aligned to sizeof(unsigned long) because it's not accessed via bitops.
  */
-u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
+u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly;
 EXPORT_SYMBOL_GPL(kvm_cpu_caps);
 
 static u32 xstate_required_size(u64 xstate_bv, bool compacted)
@@ -53,6 +53,7 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)
 }
 
 #define F feature_bit
+#define SF(name) (boot_cpu_has(X86_FEATURE_##name) ? F(name) : 0)
 
 static inline struct kvm_cpuid_entry2 *cpuid_entry2_find(
 	struct kvm_cpuid_entry2 *entries, int nent, u32 function, u32 index)
@@ -347,13 +348,13 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
 	return r;
 }
 
-static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
+/* Mask kvm_cpu_caps for @leaf with the raw CPUID capabilities of this CPU. */
+static __always_inline void __kvm_cpu_cap_mask(enum cpuid_leafs leaf)
 {
 	const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32);
 	struct kvm_cpuid_entry2 entry;
 
 	reverse_cpuid_check(leaf);
-	kvm_cpu_caps[leaf] &= mask;
 
 	cpuid_count(cpuid.function, cpuid.index,
 		    &entry.eax, &entry.ebx, &entry.ecx, &entry.edx);
@@ -361,6 +362,26 @@ static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
 	kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, cpuid.reg);
 }
 
+static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
+{
+	/* Use the "init" variant for scattered leafs. */
+	BUILD_BUG_ON(leaf >= NCAPINTS);
+
+	kvm_cpu_caps[leaf] &= mask;
+
+	__kvm_cpu_cap_mask(leaf);
+}
+
+static __always_inline void kvm_cpu_cap_init(enum cpuid_leafs leaf, u32 mask)
+{
+	/* Use the "mask" variant for hardwared-defined leafs. */
+	BUILD_BUG_ON(leaf < NCAPINTS);
+
+	kvm_cpu_caps[leaf] = mask;
+
+	__kvm_cpu_cap_mask(leaf);
+}
+
 void kvm_set_cpu_caps(void)
 {
 	unsigned int f_nx = is_efer_nx() ? F(NX) : 0;
@@ -371,12 +392,13 @@ void kvm_set_cpu_caps(void)
 	unsigned int f_gbpages = 0;
 	unsigned int f_lm = 0;
 #endif
+	memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps));
 
-	BUILD_BUG_ON(sizeof(kvm_cpu_caps) >
+	BUILD_BUG_ON(sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)) >
 		     sizeof(boot_cpu_data.x86_capability));
 
 	memcpy(&kvm_cpu_caps, &boot_cpu_data.x86_capability,
-	       sizeof(kvm_cpu_caps));
+	       sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)));
 
 	kvm_cpu_cap_mask(CPUID_1_ECX,
 		/*
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 2a0c5064497f..8925a929186c 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -7,7 +7,20 @@
 #include <asm/processor.h>
 #include <uapi/asm/kvm_para.h>
 
-extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
+/*
+ * Hardware-defined CPUID leafs that are scattered in the kernel, but need to
+ * be directly used by KVM.  Note, these word values conflict with the kernel's
+ * "bug" caps, but KVM doesn't use those.
+ */
+enum kvm_only_cpuid_leafs {
+	NR_KVM_CPU_CAPS = NCAPINTS,
+
+	NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
+};
+
+#define X86_KVM_FEATURE(w, f)		((w)*32 + (f))
+
+extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly;
 void kvm_set_cpu_caps(void);
 
 void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu);
@@ -100,6 +113,20 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
 	BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
 }
 
+/*
+ * Translate feature bits that are scattered in the kernel's cpufeatures word
+ * into KVM feature words that align with hardware's definitions.
+ */
+static __always_inline u32 __feature_translate(int x86_feature)
+{
+	return x86_feature;
+}
+
+static __always_inline u32 __feature_leaf(int x86_feature)
+{
+	return __feature_translate(x86_feature) / 32;
+}
+
 /*
  * Retrieve the bit mask from an X86_FEATURE_* definition.  Features contain
  * the hardware defined bit number (stored in bits 4:0) and a software defined
@@ -108,6 +135,8 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
  */
 static __always_inline u32 __feature_bit(int x86_feature)
 {
+	x86_feature = __feature_translate(x86_feature);
+
 	reverse_cpuid_check(x86_feature / 32);
 	return 1 << (x86_feature & 31);
 }
@@ -116,7 +145,7 @@ static __always_inline u32 __feature_bit(int x86_feature)
 
 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
 {
-	unsigned int x86_leaf = x86_feature / 32;
+	unsigned int x86_leaf = __feature_leaf(x86_feature);
 
 	reverse_cpuid_check(x86_leaf);
 	return reverse_cpuid[x86_leaf];
@@ -308,7 +337,7 @@ static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu)
 
 static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature)
 {
-	unsigned int x86_leaf = x86_feature / 32;
+	unsigned int x86_leaf = __feature_leaf(x86_feature);
 
 	reverse_cpuid_check(x86_leaf);
 	kvm_cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature);
@@ -316,7 +345,7 @@ static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature)
 
 static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature)
 {
-	unsigned int x86_leaf = x86_feature / 32;
+	unsigned int x86_leaf = __feature_leaf(x86_feature);
 
 	reverse_cpuid_check(x86_leaf);
 	kvm_cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
@@ -324,7 +353,7 @@ static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature)
 
 static __always_inline u32 kvm_cpu_cap_get(unsigned int x86_feature)
 {
-	unsigned int x86_leaf = x86_feature / 32;
+	unsigned int x86_leaf = __feature_leaf(x86_feature);
 
 	reverse_cpuid_check(x86_leaf);
 	return kvm_cpu_caps[x86_leaf] & __feature_bit(x86_feature);
-- 
2.29.2


  parent reply	other threads:[~2021-03-09  1:41 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-09  1:38 [PATCH v2 00/25] KVM SGX virtualization support Kai Huang
2021-03-09  1:38 ` [PATCH v2 01/25] x86/cpufeatures: Make SGX_LC feature bit depend on SGX bit Kai Huang
2021-03-12 21:05   ` Sean Christopherson
2021-03-09  1:39 ` [PATCH v2 02/25] x86/cpufeatures: Add SGX1 and SGX2 sub-features Kai Huang
2021-03-12 21:10   ` Sean Christopherson
2021-03-09  1:39 ` [PATCH v2 03/25] x86/sgx: Wipe out EREMOVE from sgx_free_epc_page() Kai Huang
2021-03-10  9:35   ` Kai Huang
2021-03-11  2:01   ` [PATCH v3 " Kai Huang
2021-03-12 21:21     ` Sean Christopherson
2021-03-13 10:45       ` Jarkko Sakkinen
2021-03-15  7:12         ` Kai Huang
2021-03-15 13:18           ` Jarkko Sakkinen
2021-03-15 13:19             ` Jarkko Sakkinen
2021-03-15 20:29               ` Kai Huang
2021-03-15 22:59                 ` Jarkko Sakkinen
2021-03-15 23:50                   ` Kai Huang
2021-03-15 23:11                 ` Jarkko Sakkinen
2021-03-09  1:39 ` [PATCH v2 04/25] x86/sgx: Add SGX_CHILD_PRESENT hardware error code Kai Huang
2021-03-09  1:39 ` [PATCH v2 05/25] x86/sgx: Introduce virtual EPC for use by KVM guests Kai Huang
2021-03-09  1:39 ` [PATCH v2 06/25] x86/cpu/intel: Allow SGX virtualization without Launch Control support Kai Huang
2021-03-12 21:33   ` Sean Christopherson
2021-03-09  1:39 ` [PATCH v2 07/25] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Kai Huang
2021-03-12 21:44   ` Sean Christopherson
2021-03-13 19:05     ` Jarkko Sakkinen
2021-03-13 19:07       ` Jarkko Sakkinen
2021-03-14 15:25         ` Jarkko Sakkinen
2021-03-14 15:27           ` Jarkko Sakkinen
2021-03-15  3:13             ` Kai Huang
2021-03-15 13:04               ` Jarkko Sakkinen
2021-03-15 13:51                 ` Jarkko Sakkinen
2021-03-15 20:48                   ` Kai Huang
2021-03-15 23:05                     ` Jarkko Sakkinen
2021-03-15 23:08                       ` Jarkko Sakkinen
2021-03-15 23:49                         ` Kai Huang
2021-03-16 12:44                           ` Jarkko Sakkinen
2021-03-16  1:13                         ` Sean Christopherson
2021-03-16 12:46                           ` Jarkko Sakkinen
2021-03-18  0:04                             ` Kai Huang
2021-03-09  1:39 ` [PATCH v2 08/25] x86/sgx: Expose SGX architectural definitions to the kernel Kai Huang
2021-03-12 21:58   ` Sean Christopherson
2021-03-15  3:36     ` Kai Huang
2021-03-09  1:39 ` [PATCH v2 09/25] x86/sgx: Move ENCLS leaf definitions to sgx.h Kai Huang
2021-03-09  1:39 ` [PATCH v2 10/25] x86/sgx: Add SGX2 ENCLS leaf definitions (EAUG, EMODPR and EMODT) Kai Huang
2021-03-09  1:39 ` [PATCH v2 11/25] x86/sgx: Add encls_faulted() helper Kai Huang
2021-03-09  1:39 ` [PATCH v2 12/25] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs Kai Huang
2021-03-09  1:39 ` [PATCH v2 13/25] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM Kai Huang
2021-03-15  4:08   ` Kai Huang
2021-03-09  1:39 ` [PATCH v2 14/25] x86/sgx: Move provisioning device creation out of SGX driver Kai Huang
2021-03-09  1:40 ` [PATCH v2 15/25] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-03-09  1:40 ` [PATCH v2 16/25] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-03-09  1:40 ` Kai Huang [this message]
2021-03-09  1:40 ` [PATCH v2 18/25] KVM: x86: Add reverse-CPUID lookup support for scattered SGX features Kai Huang
2021-03-09  1:40 ` [PATCH v2 19/25] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-03-09  1:40 ` [PATCH v2 20/25] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-03-09  1:40 ` [PATCH v2 21/25] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-03-09  1:40 ` [PATCH v2 22/25] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-03-09  1:40 ` [PATCH v2 23/25] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-03-09  1:40 ` [PATCH v2 24/25] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-03-09  1:41 ` [PATCH v2 25/25] KVM: x86: Add capability to grant VM access to privileged SGX attribute Kai Huang
2021-03-09  9:30 ` [PATCH v2 00/25] KVM SGX virtualization support Borislav Petkov
2021-03-09 18:08   ` Kai Huang
2021-03-09 18:49   ` Paolo Bonzini
2021-03-12 22:04     ` Sean Christopherson
2021-03-13  4:30       ` Kai Huang
2021-03-10  9:27   ` Kai Huang
2021-03-10 13:29     ` Borislav Petkov
2021-03-11  2:05       ` Kai Huang
2021-03-10 18:01   ` Jarkko Sakkinen
2021-03-10 20:44     ` Kai Huang

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