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Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0022-KVM-VMX-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch')
-rw-r--r--common/recipes-kernel/linux/linux-yocto-4.9.21/0022-KVM-VMX-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch305
1 files changed, 0 insertions, 305 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0022-KVM-VMX-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0022-KVM-VMX-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch
deleted file mode 100644
index 9a833616..00000000
--- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0022-KVM-VMX-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch
+++ /dev/null
@@ -1,305 +0,0 @@
-From 3a5351279f63e7822bbfe5c0f4ee3d5a1a5bced1 Mon Sep 17 00:00:00 2001
-From: KarimAllah Ahmed <karahmed@amazon.de>
-Date: Thu, 1 Feb 2018 22:59:45 +0100
-Subject: [PATCH 22/33] KVM/VMX: Allow direct access to MSR_IA32_SPEC_CTRL
-
-(cherry picked from commit d28b387fb74da95d69d2615732f50cceb38e9a4d)
-
-[ Based on a patch from Ashok Raj <ashok.raj@intel.com> ]
-
-Add direct access to MSR_IA32_SPEC_CTRL for guests. This is needed for
-guests that will only mitigate Spectre V2 through IBRS+IBPB and will not
-be using a retpoline+IBPB based approach.
-
-To avoid the overhead of saving and restoring the MSR_IA32_SPEC_CTRL for
-guests that do not actually use the MSR, only start saving and restoring
-when a non-zero is written to it.
-
-No attempt is made to handle STIBP here, intentionally. Filtering STIBP
-may be added in a future patch, which may require trapping all writes
-if we don't want to pass it through directly to the guest.
-
-[dwmw2: Clean up CPUID bits, save/restore manually, handle reset]
-
-Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
-Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
-Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
-Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-Reviewed-by: Jim Mattson <jmattson@google.com>
-Cc: Andrea Arcangeli <aarcange@redhat.com>
-Cc: Andi Kleen <ak@linux.intel.com>
-Cc: Jun Nakajima <jun.nakajima@intel.com>
-Cc: kvm@vger.kernel.org
-Cc: Dave Hansen <dave.hansen@intel.com>
-Cc: Tim Chen <tim.c.chen@linux.intel.com>
-Cc: Andy Lutomirski <luto@kernel.org>
-Cc: Asit Mallick <asit.k.mallick@intel.com>
-Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
-Cc: Greg KH <gregkh@linuxfoundation.org>
-Cc: Paolo Bonzini <pbonzini@redhat.com>
-Cc: Dan Williams <dan.j.williams@intel.com>
-Cc: Linus Torvalds <torvalds@linux-foundation.org>
-Cc: Ashok Raj <ashok.raj@intel.com>
-Link: https://lkml.kernel.org/r/1517522386-18410-5-git-send-email-karahmed@amazon.de
-Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- arch/x86/kvm/cpuid.c | 8 ++--
- arch/x86/kvm/cpuid.h | 11 ++++++
- arch/x86/kvm/vmx.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++-
- arch/x86/kvm/x86.c | 2 +-
- 4 files changed, 118 insertions(+), 6 deletions(-)
-
-diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
-index 4d3555b..bcebe84 100644
---- a/arch/x86/kvm/cpuid.c
-+++ b/arch/x86/kvm/cpuid.c
-@@ -357,7 +357,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
-
- /* cpuid 0x80000008.ebx */
- const u32 kvm_cpuid_8000_0008_ebx_x86_features =
-- F(IBPB);
-+ F(IBPB) | F(IBRS);
-
- /* cpuid 0xC0000001.edx */
- const u32 kvm_cpuid_C000_0001_edx_x86_features =
-@@ -382,7 +382,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
-
- /* cpuid 7.0.edx*/
- const u32 kvm_cpuid_7_0_edx_x86_features =
-- F(ARCH_CAPABILITIES);
-+ F(SPEC_CTRL) | F(ARCH_CAPABILITIES);
-
- /* all calls to cpuid_count() should be made on the same cpu */
- get_cpu();
-@@ -618,9 +618,11 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
- g_phys_as = phys_as;
- entry->eax = g_phys_as | (virt_as << 8);
- entry->edx = 0;
-- /* IBPB isn't necessarily present in hardware cpuid */
-+ /* IBRS and IBPB aren't necessarily present in hardware cpuid */
- if (boot_cpu_has(X86_FEATURE_IBPB))
- entry->ebx |= F(IBPB);
-+ if (boot_cpu_has(X86_FEATURE_IBRS))
-+ entry->ebx |= F(IBRS);
- entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
- cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
- break;
-diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
-index a69906c..841e80d 100644
---- a/arch/x86/kvm/cpuid.h
-+++ b/arch/x86/kvm/cpuid.h
-@@ -163,6 +163,17 @@ static inline bool guest_cpuid_has_ibpb(struct kvm_vcpu *vcpu)
- return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL));
- }
-
-+static inline bool guest_cpuid_has_ibrs(struct kvm_vcpu *vcpu)
-+{
-+ struct kvm_cpuid_entry2 *best;
-+
-+ best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
-+ if (best && (best->ebx & bit(X86_FEATURE_IBRS)))
-+ return true;
-+ best = kvm_find_cpuid_entry(vcpu, 7, 0);
-+ return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL));
-+}
-+
- static inline bool guest_cpuid_has_arch_capabilities(struct kvm_vcpu *vcpu)
- {
- struct kvm_cpuid_entry2 *best;
-diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
-index d8e3c02..c564d03 100644
---- a/arch/x86/kvm/vmx.c
-+++ b/arch/x86/kvm/vmx.c
-@@ -552,6 +552,7 @@ struct vcpu_vmx {
- #endif
-
- u64 arch_capabilities;
-+ u64 spec_ctrl;
-
- u32 vm_entry_controls_shadow;
- u32 vm_exit_controls_shadow;
-@@ -1847,6 +1848,29 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
- }
-
- /*
-+ * Check if MSR is intercepted for currently loaded MSR bitmap.
-+ */
-+static bool msr_write_intercepted(struct kvm_vcpu *vcpu, u32 msr)
-+{
-+ unsigned long *msr_bitmap;
-+ int f = sizeof(unsigned long);
-+
-+ if (!cpu_has_vmx_msr_bitmap())
-+ return true;
-+
-+ msr_bitmap = to_vmx(vcpu)->loaded_vmcs->msr_bitmap;
-+
-+ if (msr <= 0x1fff) {
-+ return !!test_bit(msr, msr_bitmap + 0x800 / f);
-+ } else if ((msr >= 0xc0000000) && (msr <= 0xc0001fff)) {
-+ msr &= 0x1fff;
-+ return !!test_bit(msr, msr_bitmap + 0xc00 / f);
-+ }
-+
-+ return true;
-+}
-+
-+/*
- * Check if MSR is intercepted for L01 MSR bitmap.
- */
- static bool msr_write_intercepted_l01(struct kvm_vcpu *vcpu, u32 msr)
-@@ -2978,6 +3002,13 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
- case MSR_IA32_TSC:
- msr_info->data = guest_read_tsc(vcpu);
- break;
-+ case MSR_IA32_SPEC_CTRL:
-+ if (!msr_info->host_initiated &&
-+ !guest_cpuid_has_ibrs(vcpu))
-+ return 1;
-+
-+ msr_info->data = to_vmx(vcpu)->spec_ctrl;
-+ break;
- case MSR_IA32_ARCH_CAPABILITIES:
- if (!msr_info->host_initiated &&
- !guest_cpuid_has_arch_capabilities(vcpu))
-@@ -3083,6 +3114,36 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
- case MSR_IA32_TSC:
- kvm_write_tsc(vcpu, msr_info);
- break;
-+ case MSR_IA32_SPEC_CTRL:
-+ if (!msr_info->host_initiated &&
-+ !guest_cpuid_has_ibrs(vcpu))
-+ return 1;
-+
-+ /* The STIBP bit doesn't fault even if it's not advertised */
-+ if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP))
-+ return 1;
-+
-+ vmx->spec_ctrl = data;
-+
-+ if (!data)
-+ break;
-+
-+ /*
-+ * For non-nested:
-+ * When it's written (to non-zero) for the first time, pass
-+ * it through.
-+ *
-+ * For nested:
-+ * The handling of the MSR bitmap for L2 guests is done in
-+ * nested_vmx_merge_msr_bitmap. We should not touch the
-+ * vmcs02.msr_bitmap here since it gets completely overwritten
-+ * in the merging. We update the vmcs01 here for L1 as well
-+ * since it will end up touching the MSR anyway now.
-+ */
-+ vmx_disable_intercept_for_msr(vmx->vmcs01.msr_bitmap,
-+ MSR_IA32_SPEC_CTRL,
-+ MSR_TYPE_RW);
-+ break;
- case MSR_IA32_PRED_CMD:
- if (!msr_info->host_initiated &&
- !guest_cpuid_has_ibpb(vcpu))
-@@ -5216,6 +5277,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
- u64 cr0;
-
- vmx->rmode.vm86_active = 0;
-+ vmx->spec_ctrl = 0;
-
- vmx->soft_vnmi_blocked = 0;
-
-@@ -8806,6 +8868,15 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
-
- vmx_arm_hv_timer(vcpu);
-
-+ /*
-+ * If this vCPU has touched SPEC_CTRL, restore the guest's value if
-+ * it's non-zero. Since vmentry is serialising on affected CPUs, there
-+ * is no need to worry about the conditional branch over the wrmsr
-+ * being speculatively taken.
-+ */
-+ if (vmx->spec_ctrl)
-+ wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
-+
- vmx->__launched = vmx->loaded_vmcs->launched;
- asm(
- /* Store host registers */
-@@ -8924,6 +8995,27 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
- #endif
- );
-
-+ /*
-+ * We do not use IBRS in the kernel. If this vCPU has used the
-+ * SPEC_CTRL MSR it may have left it on; save the value and
-+ * turn it off. This is much more efficient than blindly adding
-+ * it to the atomic save/restore list. Especially as the former
-+ * (Saving guest MSRs on vmexit) doesn't even exist in KVM.
-+ *
-+ * For non-nested case:
-+ * If the L01 MSR bitmap does not intercept the MSR, then we need to
-+ * save it.
-+ *
-+ * For nested case:
-+ * If the L02 MSR bitmap does not intercept the MSR, then we need to
-+ * save it.
-+ */
-+ if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))
-+ rdmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
-+
-+ if (vmx->spec_ctrl)
-+ wrmsrl(MSR_IA32_SPEC_CTRL, 0);
-+
- /* Eliminate branch target predictions from guest mode */
- vmexit_fill_RSB();
-
-@@ -9476,7 +9568,7 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
- unsigned long *msr_bitmap_l1;
- unsigned long *msr_bitmap_l0 = to_vmx(vcpu)->nested.vmcs02.msr_bitmap;
- /*
-- * pred_cmd is trying to verify two things:
-+ * pred_cmd & spec_ctrl are trying to verify two things:
- *
- * 1. L0 gave a permission to L1 to actually passthrough the MSR. This
- * ensures that we do not accidentally generate an L02 MSR bitmap
-@@ -9489,9 +9581,10 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
- * the MSR.
- */
- bool pred_cmd = msr_write_intercepted_l01(vcpu, MSR_IA32_PRED_CMD);
-+ bool spec_ctrl = msr_write_intercepted_l01(vcpu, MSR_IA32_SPEC_CTRL);
-
- if (!nested_cpu_has_virt_x2apic_mode(vmcs12) &&
-- !pred_cmd)
-+ !pred_cmd && !spec_ctrl)
- return false;
-
- page = nested_get_page(vcpu, vmcs12->msr_bitmap);
-@@ -9527,6 +9620,12 @@ static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
- }
- }
-
-+ if (spec_ctrl)
-+ nested_vmx_disable_intercept_for_msr(
-+ msr_bitmap_l1, msr_bitmap_l0,
-+ MSR_IA32_SPEC_CTRL,
-+ MSR_TYPE_R | MSR_TYPE_W);
-+
- if (pred_cmd)
- nested_vmx_disable_intercept_for_msr(
- msr_bitmap_l1, msr_bitmap_l0,
-diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
-index d01742e..d2ea523 100644
---- a/arch/x86/kvm/x86.c
-+++ b/arch/x86/kvm/x86.c
-@@ -975,7 +975,7 @@ static u32 msrs_to_save[] = {
- #endif
- MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
- MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
-- MSR_IA32_ARCH_CAPABILITIES
-+ MSR_IA32_SPEC_CTRL, MSR_IA32_ARCH_CAPABILITIES
- };
-
- static unsigned num_msrs_to_save;
---
-2.7.4
-
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-04-24 23:53:05 +0000