diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0023-KVM-SVM-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch')
-rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0023-KVM-SVM-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch | 192 |
1 files changed, 0 insertions, 192 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0023-KVM-SVM-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0023-KVM-SVM-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch deleted file mode 100644 index 905134c7..00000000 --- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0023-KVM-SVM-Allow-direct-access-to-MSR_IA32_SPEC_CTRL.patch +++ /dev/null @@ -1,192 +0,0 @@ -From c8b2b4bc3e5eddb48f6eda57e9138a2ea2d39345 Mon Sep 17 00:00:00 2001 -From: KarimAllah Ahmed <karahmed@amazon.de> -Date: Sat, 3 Feb 2018 15:56:23 +0100 -Subject: [PATCH 23/33] KVM/SVM: Allow direct access to MSR_IA32_SPEC_CTRL - -(cherry picked from commit b2ac58f90540e39324e7a29a7ad471407ae0bf48) - -[ Based on a patch from Paolo Bonzini <pbonzini@redhat.com> ] - -... basically doing exactly what we do for VMX: - -- Passthrough SPEC_CTRL to guests (if enabled in guest CPUID) -- Save and restore SPEC_CTRL around VMExit and VMEntry only if the guest - actually used it. - -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> -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/1517669783-20732-1-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/svm.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ - 1 file changed, 88 insertions(+) - -diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c -index 43e45b9..4a36977 100644 ---- a/arch/x86/kvm/svm.c -+++ b/arch/x86/kvm/svm.c -@@ -183,6 +183,8 @@ struct vcpu_svm { - u64 gs_base; - } host; - -+ u64 spec_ctrl; -+ - u32 *msrpm; - - ulong nmi_iret_rip; -@@ -248,6 +250,7 @@ static const struct svm_direct_access_msrs { - { .index = MSR_CSTAR, .always = true }, - { .index = MSR_SYSCALL_MASK, .always = true }, - #endif -+ { .index = MSR_IA32_SPEC_CTRL, .always = false }, - { .index = MSR_IA32_PRED_CMD, .always = false }, - { .index = MSR_IA32_LASTBRANCHFROMIP, .always = false }, - { .index = MSR_IA32_LASTBRANCHTOIP, .always = false }, -@@ -863,6 +866,25 @@ static bool valid_msr_intercept(u32 index) - return false; - } - -+static bool msr_write_intercepted(struct kvm_vcpu *vcpu, unsigned msr) -+{ -+ u8 bit_write; -+ unsigned long tmp; -+ u32 offset; -+ u32 *msrpm; -+ -+ msrpm = is_guest_mode(vcpu) ? to_svm(vcpu)->nested.msrpm: -+ to_svm(vcpu)->msrpm; -+ -+ offset = svm_msrpm_offset(msr); -+ bit_write = 2 * (msr & 0x0f) + 1; -+ tmp = msrpm[offset]; -+ -+ BUG_ON(offset == MSR_INVALID); -+ -+ return !!test_bit(bit_write, &tmp); -+} -+ - static void set_msr_interception(u32 *msrpm, unsigned msr, - int read, int write) - { -@@ -1534,6 +1556,8 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) - u32 dummy; - u32 eax = 1; - -+ svm->spec_ctrl = 0; -+ - if (!init_event) { - svm->vcpu.arch.apic_base = APIC_DEFAULT_PHYS_BASE | - MSR_IA32_APICBASE_ENABLE; -@@ -3515,6 +3539,13 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) - case MSR_VM_CR: - msr_info->data = svm->nested.vm_cr_msr; - break; -+ case MSR_IA32_SPEC_CTRL: -+ if (!msr_info->host_initiated && -+ !guest_cpuid_has_ibrs(vcpu)) -+ return 1; -+ -+ msr_info->data = svm->spec_ctrl; -+ break; - case MSR_IA32_UCODE_REV: - msr_info->data = 0x01000065; - break; -@@ -3599,6 +3630,33 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) - case MSR_IA32_TSC: - kvm_write_tsc(vcpu, msr); - break; -+ case MSR_IA32_SPEC_CTRL: -+ if (!msr->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; -+ -+ svm->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_svm_vmrun_msrpm. -+ * We update the L1 MSR bit as well since it will end up -+ * touching the MSR anyway now. -+ */ -+ set_msr_interception(svm->msrpm, MSR_IA32_SPEC_CTRL, 1, 1); -+ break; - case MSR_IA32_PRED_CMD: - if (!msr->host_initiated && - !guest_cpuid_has_ibpb(vcpu)) -@@ -4842,6 +4900,15 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu) - - local_irq_enable(); - -+ /* -+ * 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 (svm->spec_ctrl) -+ wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl); -+ - asm volatile ( - "push %%" _ASM_BP "; \n\t" - "mov %c[rbx](%[svm]), %%" _ASM_BX " \n\t" -@@ -4934,6 +5001,27 @@ static void svm_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, svm->spec_ctrl); -+ -+ if (svm->spec_ctrl) -+ wrmsrl(MSR_IA32_SPEC_CTRL, 0); -+ - /* Eliminate branch target predictions from guest mode */ - vmexit_fill_RSB(); - --- -2.7.4 - |