August 2022 - Linux-stable-mirror

FAILED: patch "[PATCH] KVM: x86: Signal #GP, not -EPERM, on bad" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS) Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e. the intent is to inject a #GP, not exit to userspace due to an unhandled emulation case. Returning '-1' gets interpreted as -EPERM up the stack and effecitvely kills the guest. Fixes: 890ca9aefa78 ("KVM: Add MCE support") Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10) | 1) != ~(u64)0) - return -1; + return 1; /* MCi_STATUS */ if (!msr_info->host_initiated && (offset & 0x3) == 1 && data != 0) { if (!can_set_mci_status(vcpu)) - return -1; + return 1; } vcpu->arch.mce_banks[offset] = data;

2 years, 5 months

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FAILED: patch "[PATCH] KVM: x86: Signal #GP, not -EPERM, on bad" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS) Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e. the intent is to inject a #GP, not exit to userspace due to an unhandled emulation case. Returning '-1' gets interpreted as -EPERM up the stack and effecitvely kills the guest. Fixes: 890ca9aefa78 ("KVM: Add MCE support") Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10) | 1) != ~(u64)0) - return -1; + return 1; /* MCi_STATUS */ if (!msr_info->host_initiated && (offset & 0x3) == 1 && data != 0) { if (!can_set_mci_status(vcpu)) - return -1; + return 1; } vcpu->arch.mce_banks[offset] = data;

2 years, 5 months

1
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0 0

FAILED: patch "[PATCH] KVM: x86: Signal #GP, not -EPERM, on bad" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS) Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e. the intent is to inject a #GP, not exit to userspace due to an unhandled emulation case. Returning '-1' gets interpreted as -EPERM up the stack and effecitvely kills the guest. Fixes: 890ca9aefa78 ("KVM: Add MCE support") Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10) | 1) != ~(u64)0) - return -1; + return 1; /* MCi_STATUS */ if (!msr_info->host_initiated && (offset & 0x3) == 1 && data != 0) { if (!can_set_mci_status(vcpu)) - return -1; + return 1; } vcpu->arch.mce_banks[offset] = data;

2 years, 5 months

1
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FAILED: patch "[PATCH] KVM: x86: Signal #GP, not -EPERM, on bad" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS) Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e. the intent is to inject a #GP, not exit to userspace due to an unhandled emulation case. Returning '-1' gets interpreted as -EPERM up the stack and effecitvely kills the guest. Fixes: 890ca9aefa78 ("KVM: Add MCE support") Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10) | 1) != ~(u64)0) - return -1; + return 1; /* MCi_STATUS */ if (!msr_info->host_initiated && (offset & 0x3) == 1 && data != 0) { if (!can_set_mci_status(vcpu)) - return -1; + return 1; } vcpu->arch.mce_banks[offset] = data;

2 years, 5 months

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FAILED: patch "[PATCH] KVM: x86: Signal #GP, not -EPERM, on bad" failed to apply to 5.18-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS) Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e. the intent is to inject a #GP, not exit to userspace due to an unhandled emulation case. Returning '-1' gets interpreted as -EPERM up the stack and effecitvely kills the guest. Fixes: 890ca9aefa78 ("KVM: Add MCE support") Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10) | 1) != ~(u64)0) - return -1; + return 1; /* MCi_STATUS */ if (!msr_info->host_initiated && (offset & 0x3) == 1 && data != 0) { if (!can_set_mci_status(vcpu)) - return -1; + return 1; } vcpu->arch.mce_banks[offset] = data;

2 years, 5 months

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FAILED: patch "[PATCH] KVM: x86: Signal #GP, not -EPERM, on bad" failed to apply to 5.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS) Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e. the intent is to inject a #GP, not exit to userspace due to an unhandled emulation case. Returning '-1' gets interpreted as -EPERM up the stack and effecitvely kills the guest. Fixes: 890ca9aefa78 ("KVM: Add MCE support") Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10) | 1) != ~(u64)0) - return -1; + return 1; /* MCi_STATUS */ if (!msr_info->host_initiated && (offset & 0x3) == 1 && data != 0) { if (!can_set_mci_status(vcpu)) - return -1; + return 1; } vcpu->arch.mce_banks[offset] = data;

2 years, 5 months

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FAILED: patch "[PATCH] KVM: nVMX: Always enable TSC scaling for L2 when it was" failed to apply to 5.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 156b9d76e8822f2956c15029acf2d4b171502f3a Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov <vkuznets(a)redhat.com> Date: Tue, 12 Jul 2022 15:50:09 +0200 Subject: [PATCH] KVM: nVMX: Always enable TSC scaling for L2 when it was enabled for L1 Windows 10/11 guests with Hyper-V role (WSL2) enabled are observed to hang upon boot or shortly after when a non-default TSC frequency was set for L1. The issue is observed on a host where TSC scaling is supported. The problem appears to be that Windows doesn't use TSC scaling for its guests, even when the feature is advertised, and KVM filters SECONDARY_EXEC_TSC_SCALING out when creating L2 controls from L1's VMCS. This leads to L2 running with the default frequency (matching host's) while L1 is running with an altered one. Keep SECONDARY_EXEC_TSC_SCALING in secondary exec controls for L2 when it was set for L1. TSC_MULTIPLIER is already correctly computed and written by prepare_vmcs02(). Signed-off-by: Vitaly Kuznetsov <vkuznets(a)redhat.com> Fixes: d041b5ea93352b ("KVM: nVMX: Enable nested TSC scaling") Cc: stable(a)vger.kernel.org Reviewed-by: Maxim Levitsky <mlevitsk(a)redhat.com> Link: https://lore.kernel.org/r/20220712135009.952805-1-vkuznets@redhat.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 778f82015f03..bfa366938c49 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2284,7 +2284,6 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0 SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY | SECONDARY_EXEC_APIC_REGISTER_VIRT | SECONDARY_EXEC_ENABLE_VMFUNC | - SECONDARY_EXEC_TSC_SCALING | SECONDARY_EXEC_DESC); if (nested_cpu_has(vmcs12,

2 years, 5 months

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FAILED: patch "[PATCH] KVM: nVMX: Attempt to load PERF_GLOBAL_CTRL on nVMX xfer iff" failed to apply to 5.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 4496a6f9b45e8cd83343ad86a3984d614e22cf54 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Fri, 22 Jul 2022 22:44:08 +0000 Subject: [PATCH] KVM: nVMX: Attempt to load PERF_GLOBAL_CTRL on nVMX xfer iff it exists Attempt to load PERF_GLOBAL_CTRL during nested VM-Enter/VM-Exit if and only if the MSR exists (according to the guest vCPU model). KVM has very misguided handling of VM_{ENTRY,EXIT}_LOAD_IA32_PERF_GLOBAL_CTRL and attempts to force the nVMX MSR settings to match the vPMU model, i.e. to hide/expose the control based on whether or not the MSR exists from the guest's perspective. KVM's modifications fail to handle the scenario where the vPMU is hidden from the guest _after_ being exposed to the guest, e.g. by userspace doing multiple KVM_SET_CPUID2 calls, which is allowed if done before any KVM_RUN. nested_vmx_pmu_refresh() is called if and only if there's a recognized vPMU, i.e. KVM will leave the bits in the allow state and then ultimately reject the MSR load and WARN. KVM should not force the VMX MSRs in the first place. KVM taking control of the MSRs was a misguided attempt at mimicking what commit 5f76f6f5ff96 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled", 2018-10-01) did for MPX. However, the MPX commit was a workaround for another KVM bug and not something that should be imitated (and it should never been done in the first place). In other words, KVM's ABI _should_ be that userspace has full control over the MSRs, at which point triggering the WARN that loading the MSR must not fail is trivial. The intent of the WARN is still valid; KVM has consistency checks to ensure that vmcs12->{guest,host}_ia32_perf_global_ctrl is valid. The problem is that '0' must be considered a valid value at all times, and so the simple/obvious solution is to just not actually load the MSR when it does not exist. It is userspace's responsibility to provide a sane vCPU model, i.e. KVM is well within its ABI and Intel's VMX architecture to skip the loads if the MSR does not exist. Fixes: 03a8871add95 ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20220722224409.1336532-5-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index c1c85fd75d42..819cfd926954 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2623,6 +2623,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, } if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) && + intel_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu)) && WARN_ON_ONCE(kvm_set_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL, vmcs12->guest_ia32_perf_global_ctrl))) { *entry_failure_code = ENTRY_FAIL_DEFAULT; @@ -4333,7 +4334,8 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, vmcs_write64(GUEST_IA32_PAT, vmcs12->host_ia32_pat); vcpu->arch.pat = vmcs12->host_ia32_pat; } - if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) + if ((vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) && + intel_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu))) WARN_ON_ONCE(kvm_set_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL, vmcs12->host_ia32_perf_global_ctrl));

2 years, 5 months

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FAILED: patch "[PATCH] KVM: nVMX: Attempt to load PERF_GLOBAL_CTRL on nVMX xfer iff" failed to apply to 5.18-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 4496a6f9b45e8cd83343ad86a3984d614e22cf54 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Fri, 22 Jul 2022 22:44:08 +0000 Subject: [PATCH] KVM: nVMX: Attempt to load PERF_GLOBAL_CTRL on nVMX xfer iff it exists Attempt to load PERF_GLOBAL_CTRL during nested VM-Enter/VM-Exit if and only if the MSR exists (according to the guest vCPU model). KVM has very misguided handling of VM_{ENTRY,EXIT}_LOAD_IA32_PERF_GLOBAL_CTRL and attempts to force the nVMX MSR settings to match the vPMU model, i.e. to hide/expose the control based on whether or not the MSR exists from the guest's perspective. KVM's modifications fail to handle the scenario where the vPMU is hidden from the guest _after_ being exposed to the guest, e.g. by userspace doing multiple KVM_SET_CPUID2 calls, which is allowed if done before any KVM_RUN. nested_vmx_pmu_refresh() is called if and only if there's a recognized vPMU, i.e. KVM will leave the bits in the allow state and then ultimately reject the MSR load and WARN. KVM should not force the VMX MSRs in the first place. KVM taking control of the MSRs was a misguided attempt at mimicking what commit 5f76f6f5ff96 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled", 2018-10-01) did for MPX. However, the MPX commit was a workaround for another KVM bug and not something that should be imitated (and it should never been done in the first place). In other words, KVM's ABI _should_ be that userspace has full control over the MSRs, at which point triggering the WARN that loading the MSR must not fail is trivial. The intent of the WARN is still valid; KVM has consistency checks to ensure that vmcs12->{guest,host}_ia32_perf_global_ctrl is valid. The problem is that '0' must be considered a valid value at all times, and so the simple/obvious solution is to just not actually load the MSR when it does not exist. It is userspace's responsibility to provide a sane vCPU model, i.e. KVM is well within its ABI and Intel's VMX architecture to skip the loads if the MSR does not exist. Fixes: 03a8871add95 ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20220722224409.1336532-5-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index c1c85fd75d42..819cfd926954 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2623,6 +2623,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, } if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) && + intel_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu)) && WARN_ON_ONCE(kvm_set_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL, vmcs12->guest_ia32_perf_global_ctrl))) { *entry_failure_code = ENTRY_FAIL_DEFAULT; @@ -4333,7 +4334,8 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, vmcs_write64(GUEST_IA32_PAT, vmcs12->host_ia32_pat); vcpu->arch.pat = vmcs12->host_ia32_pat; } - if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) + if ((vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) && + intel_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu))) WARN_ON_ONCE(kvm_set_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL, vmcs12->host_ia32_perf_global_ctrl));

2 years, 5 months

1
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FAILED: patch "[PATCH] KVM: nVMX: Attempt to load PERF_GLOBAL_CTRL on nVMX xfer iff" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 4496a6f9b45e8cd83343ad86a3984d614e22cf54 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Fri, 22 Jul 2022 22:44:08 +0000 Subject: [PATCH] KVM: nVMX: Attempt to load PERF_GLOBAL_CTRL on nVMX xfer iff it exists Attempt to load PERF_GLOBAL_CTRL during nested VM-Enter/VM-Exit if and only if the MSR exists (according to the guest vCPU model). KVM has very misguided handling of VM_{ENTRY,EXIT}_LOAD_IA32_PERF_GLOBAL_CTRL and attempts to force the nVMX MSR settings to match the vPMU model, i.e. to hide/expose the control based on whether or not the MSR exists from the guest's perspective. KVM's modifications fail to handle the scenario where the vPMU is hidden from the guest _after_ being exposed to the guest, e.g. by userspace doing multiple KVM_SET_CPUID2 calls, which is allowed if done before any KVM_RUN. nested_vmx_pmu_refresh() is called if and only if there's a recognized vPMU, i.e. KVM will leave the bits in the allow state and then ultimately reject the MSR load and WARN. KVM should not force the VMX MSRs in the first place. KVM taking control of the MSRs was a misguided attempt at mimicking what commit 5f76f6f5ff96 ("KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled", 2018-10-01) did for MPX. However, the MPX commit was a workaround for another KVM bug and not something that should be imitated (and it should never been done in the first place). In other words, KVM's ABI _should_ be that userspace has full control over the MSRs, at which point triggering the WARN that loading the MSR must not fail is trivial. The intent of the WARN is still valid; KVM has consistency checks to ensure that vmcs12->{guest,host}_ia32_perf_global_ctrl is valid. The problem is that '0' must be considered a valid value at all times, and so the simple/obvious solution is to just not actually load the MSR when it does not exist. It is userspace's responsibility to provide a sane vCPU model, i.e. KVM is well within its ABI and Intel's VMX architecture to skip the loads if the MSR does not exist. Fixes: 03a8871add95 ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control") Cc: stable(a)vger.kernel.org Signed-off-by: Sean Christopherson <seanjc(a)google.com> Message-Id: <20220722224409.1336532-5-seanjc(a)google.com> Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index c1c85fd75d42..819cfd926954 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2623,6 +2623,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, } if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) && + intel_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu)) && WARN_ON_ONCE(kvm_set_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL, vmcs12->guest_ia32_perf_global_ctrl))) { *entry_failure_code = ENTRY_FAIL_DEFAULT; @@ -4333,7 +4334,8 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, vmcs_write64(GUEST_IA32_PAT, vmcs12->host_ia32_pat); vcpu->arch.pat = vmcs12->host_ia32_pat; } - if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) + if ((vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) && + intel_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu))) WARN_ON_ONCE(kvm_set_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL, vmcs12->host_ia32_perf_global_ctrl));

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