March 2025 - Linux-stable-mirror

FAILED: patch "[PATCH] KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 189ecdb3e112da703ac0699f4ec76aa78122f911 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031003-unstitch-arbitrate-baa1@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 189ecdb3e112da703ac0699f4ec76aa78122f911 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 27 Feb 2025 14:24:10 -0800 Subject: [PATCH] KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs Snapshot the host's DEBUGCTL after disabling IRQs, as perf can toggle debugctl bits from IRQ context, e.g. when enabling/disabling events via smp_call_function_single(). Taking the snapshot (long) before IRQs are disabled could result in KVM effectively clobbering DEBUGCTL due to using a stale snapshot. Cc: stable(a)vger.kernel.org Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria(a)amd.com> Link: https://lore.kernel.org/r/20250227222411.3490595-6-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5c6fd0edc41f..12d5f47c1bbe 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4968,7 +4968,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* Save host pkru register if supported */ vcpu->arch.host_pkru = read_pkru(); - vcpu->arch.host_debugctl = get_debugctlmsr(); /* Apply any externally detected TSC adjustments (due to suspend) */ if (unlikely(vcpu->arch.tsc_offset_adjustment)) { @@ -10969,6 +10968,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) set_debugreg(0, 7); } + vcpu->arch.host_debugctl = get_debugctlmsr(); + guest_timing_enter_irqoff(); for (;;) {

3 months, 1 week

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FAILED: patch "[PATCH] KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 189ecdb3e112da703ac0699f4ec76aa78122f911 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031002-campsite-railroad-4d13@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 189ecdb3e112da703ac0699f4ec76aa78122f911 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 27 Feb 2025 14:24:10 -0800 Subject: [PATCH] KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs Snapshot the host's DEBUGCTL after disabling IRQs, as perf can toggle debugctl bits from IRQ context, e.g. when enabling/disabling events via smp_call_function_single(). Taking the snapshot (long) before IRQs are disabled could result in KVM effectively clobbering DEBUGCTL due to using a stale snapshot. Cc: stable(a)vger.kernel.org Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria(a)amd.com> Link: https://lore.kernel.org/r/20250227222411.3490595-6-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5c6fd0edc41f..12d5f47c1bbe 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4968,7 +4968,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* Save host pkru register if supported */ vcpu->arch.host_pkru = read_pkru(); - vcpu->arch.host_debugctl = get_debugctlmsr(); /* Apply any externally detected TSC adjustments (due to suspend) */ if (unlikely(vcpu->arch.tsc_offset_adjustment)) { @@ -10969,6 +10968,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) set_debugreg(0, 7); } + vcpu->arch.host_debugctl = get_debugctlmsr(); + guest_timing_enter_irqoff(); for (;;) {

3 months, 1 week

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FAILED: patch "[PATCH] KVM: x86: Snapshot the host's DEBUGCTL in common x86" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x fb71c795935652fa20eaf9517ca9547f5af99a76 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031034-twister-stash-ba87@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fb71c795935652fa20eaf9517ca9547f5af99a76 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 27 Feb 2025 14:24:08 -0800 Subject: [PATCH] KVM: x86: Snapshot the host's DEBUGCTL in common x86 Move KVM's snapshot of DEBUGCTL to kvm_vcpu_arch and take the snapshot in common x86, so that SVM can also use the snapshot. Opportunistically change the field to a u64. While bits 63:32 are reserved on AMD, not mentioned at all in Intel's SDM, and managed as an "unsigned long" by the kernel, DEBUGCTL is an MSR and therefore a 64-bit value. Reviewed-by: Xiaoyao Li <xiaoyao.li(a)intel.com> Cc: stable(a)vger.kernel.org Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria(a)amd.com> Link: https://lore.kernel.org/r/20250227222411.3490595-4-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0b7af5902ff7..32ae3aa50c7e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -780,6 +780,7 @@ struct kvm_vcpu_arch { u32 pkru; u32 hflags; u64 efer; + u64 host_debugctl; u64 apic_base; struct kvm_lapic *apic; /* kernel irqchip context */ bool load_eoi_exitmap_pending; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 6c56d5235f0f..3b92f893b239 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1514,16 +1514,12 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, */ void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { - struct vcpu_vmx *vmx = to_vmx(vcpu); - if (vcpu->scheduled_out && !kvm_pause_in_guest(vcpu->kvm)) shrink_ple_window(vcpu); vmx_vcpu_load_vmcs(vcpu, cpu, NULL); vmx_vcpu_pi_load(vcpu, cpu); - - vmx->host_debugctlmsr = get_debugctlmsr(); } void vmx_vcpu_put(struct kvm_vcpu *vcpu) @@ -7458,8 +7454,8 @@ fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) } /* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */ - if (vmx->host_debugctlmsr) - update_debugctlmsr(vmx->host_debugctlmsr); + if (vcpu->arch.host_debugctl) + update_debugctlmsr(vcpu->arch.host_debugctl); #ifndef CONFIG_X86_64 /* diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 8b111ce1087c..951e44dc9d0e 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -340,8 +340,6 @@ struct vcpu_vmx { /* apic deadline value in host tsc */ u64 hv_deadline_tsc; - unsigned long host_debugctlmsr; - /* * Only bits masked by msr_ia32_feature_control_valid_bits can be set in * msr_ia32_feature_control. FEAT_CTL_LOCKED is always included diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 02159c967d29..5c6fd0edc41f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4968,6 +4968,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* Save host pkru register if supported */ vcpu->arch.host_pkru = read_pkru(); + vcpu->arch.host_debugctl = get_debugctlmsr(); /* Apply any externally detected TSC adjustments (due to suspend) */ if (unlikely(vcpu->arch.tsc_offset_adjustment)) {

3 months, 1 week

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FAILED: patch "[PATCH] KVM: x86: Snapshot the host's DEBUGCTL in common x86" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x fb71c795935652fa20eaf9517ca9547f5af99a76 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031034-latitude-stinking-09c1@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From fb71c795935652fa20eaf9517ca9547f5af99a76 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Thu, 27 Feb 2025 14:24:08 -0800 Subject: [PATCH] KVM: x86: Snapshot the host's DEBUGCTL in common x86 Move KVM's snapshot of DEBUGCTL to kvm_vcpu_arch and take the snapshot in common x86, so that SVM can also use the snapshot. Opportunistically change the field to a u64. While bits 63:32 are reserved on AMD, not mentioned at all in Intel's SDM, and managed as an "unsigned long" by the kernel, DEBUGCTL is an MSR and therefore a 64-bit value. Reviewed-by: Xiaoyao Li <xiaoyao.li(a)intel.com> Cc: stable(a)vger.kernel.org Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria(a)amd.com> Link: https://lore.kernel.org/r/20250227222411.3490595-4-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0b7af5902ff7..32ae3aa50c7e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -780,6 +780,7 @@ struct kvm_vcpu_arch { u32 pkru; u32 hflags; u64 efer; + u64 host_debugctl; u64 apic_base; struct kvm_lapic *apic; /* kernel irqchip context */ bool load_eoi_exitmap_pending; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 6c56d5235f0f..3b92f893b239 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1514,16 +1514,12 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, */ void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { - struct vcpu_vmx *vmx = to_vmx(vcpu); - if (vcpu->scheduled_out && !kvm_pause_in_guest(vcpu->kvm)) shrink_ple_window(vcpu); vmx_vcpu_load_vmcs(vcpu, cpu, NULL); vmx_vcpu_pi_load(vcpu, cpu); - - vmx->host_debugctlmsr = get_debugctlmsr(); } void vmx_vcpu_put(struct kvm_vcpu *vcpu) @@ -7458,8 +7454,8 @@ fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) } /* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */ - if (vmx->host_debugctlmsr) - update_debugctlmsr(vmx->host_debugctlmsr); + if (vcpu->arch.host_debugctl) + update_debugctlmsr(vcpu->arch.host_debugctl); #ifndef CONFIG_X86_64 /* diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 8b111ce1087c..951e44dc9d0e 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -340,8 +340,6 @@ struct vcpu_vmx { /* apic deadline value in host tsc */ u64 hv_deadline_tsc; - unsigned long host_debugctlmsr; - /* * Only bits masked by msr_ia32_feature_control_valid_bits can be set in * msr_ia32_feature_control. FEAT_CTL_LOCKED is always included diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 02159c967d29..5c6fd0edc41f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4968,6 +4968,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* Save host pkru register if supported */ vcpu->arch.host_pkru = read_pkru(); + vcpu->arch.host_debugctl = get_debugctlmsr(); /* Apply any externally detected TSC adjustments (due to suspend) */ if (unlikely(vcpu->arch.tsc_offset_adjustment)) {

3 months, 1 week

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FAILED: patch "[PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the" 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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x be45bc4eff33d9a7dae84a2150f242a91a617402 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031025-hurry-muster-0e93@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From be45bc4eff33d9a7dae84a2150f242a91a617402 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Mon, 24 Feb 2025 08:54:41 -0800 Subject: [PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow Enable/disable local IRQs, i.e. set/clear RFLAGS.IF, in the common svm_vcpu_enter_exit() just after/before guest_state_{enter,exit}_irqoff() so that VMRUN is not executed in an STI shadow. AMD CPUs have a quirk (some would say "bug"), where the STI shadow bleeds into the guest's intr_state field if a #VMEXIT occurs during injection of an event, i.e. if the VMRUN doesn't complete before the subsequent #VMEXIT. The spurious "interrupts masked" state is relatively benign, as it only occurs during event injection and is transient. Because KVM is already injecting an event, the guest can't be in HLT, and if KVM is querying IRQ blocking for injection, then KVM would need to force an immediate exit anyways since injecting multiple events is impossible. However, because KVM copies int_state verbatim from vmcb02 to vmcb12, the spurious STI shadow is visible to L1 when running a nested VM, which can trip sanity checks, e.g. in VMware's VMM. Hoist the STI+CLI all the way to C code, as the aforementioned calls to guest_state_{enter,exit}_irqoff() already inform lockdep that IRQs are enabled/disabled, and taking a fault on VMRUN with RFLAGS.IF=1 is already possible. I.e. if there's kernel code that is confused by running with RFLAGS.IF=1, then it's already a problem. In practice, since GIF=0 also blocks NMIs, the only change in exposure to non-KVM code (relative to surrounding VMRUN with STI+CLI) is exception handling code, and except for the kvm_rebooting=1 case, all exception in the core VM-Enter/VM-Exit path are fatal. Use the "raw" variants to enable/disable IRQs to avoid tracing in the "no instrumentation" code; the guest state helpers also take care of tracing IRQ state. Oppurtunstically document why KVM needs to do STI in the first place. Reported-by: Doug Covelli <doug.covelli(a)broadcom.com> Closes: https://lore.kernel.org/all/CADH9ctBs1YPmE4aCfGPNBwA10cA8RuAk2gO7542DjMZgs4… Fixes: f14eec0a3203 ("KVM: SVM: move more vmentry code to assembly") Cc: stable(a)vger.kernel.org Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20250224165442.2338294-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a713c803a3a3..0d299f3f921e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4189,6 +4189,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in guest_state_enter_irqoff(); + /* + * Set RFLAGS.IF prior to VMRUN, as the host's RFLAGS.IF at the time of + * VMRUN controls whether or not physical IRQs are masked (KVM always + * runs with V_INTR_MASKING_MASK). Toggle RFLAGS.IF here to avoid the + * temptation to do STI+VMRUN+CLI, as AMD CPUs bleed the STI shadow + * into guest state if delivery of an event during VMRUN triggers a + * #VMEXIT, and the guest_state transitions already tell lockdep that + * IRQs are being enabled/disabled. Note! GIF=0 for the entirety of + * this path, so IRQs aren't actually unmasked while running host code. + */ + raw_local_irq_enable(); + amd_clear_divider(); if (sev_es_guest(vcpu->kvm)) @@ -4197,6 +4209,8 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in else __svm_vcpu_run(svm, spec_ctrl_intercepted); + raw_local_irq_disable(); + guest_state_exit_irqoff(); } diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S index 2ed80aea3bb1..0c61153b275f 100644 --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -170,12 +170,8 @@ SYM_FUNC_START(__svm_vcpu_run) mov VCPU_RDI(%_ASM_DI), %_ASM_DI /* Enter guest mode */ - sti - 3: vmrun %_ASM_AX 4: - cli - /* Pop @svm to RAX while it's the only available register. */ pop %_ASM_AX @@ -340,12 +336,8 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run) mov KVM_VMCB_pa(%rax), %rax /* Enter guest mode */ - sti - 1: vmrun %rax - -2: cli - +2: /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_VMEXIT

3 months, 1 week

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FAILED: patch "[PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the" 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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x be45bc4eff33d9a7dae84a2150f242a91a617402 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031024-bootleg-parkway-393c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From be45bc4eff33d9a7dae84a2150f242a91a617402 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Mon, 24 Feb 2025 08:54:41 -0800 Subject: [PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow Enable/disable local IRQs, i.e. set/clear RFLAGS.IF, in the common svm_vcpu_enter_exit() just after/before guest_state_{enter,exit}_irqoff() so that VMRUN is not executed in an STI shadow. AMD CPUs have a quirk (some would say "bug"), where the STI shadow bleeds into the guest's intr_state field if a #VMEXIT occurs during injection of an event, i.e. if the VMRUN doesn't complete before the subsequent #VMEXIT. The spurious "interrupts masked" state is relatively benign, as it only occurs during event injection and is transient. Because KVM is already injecting an event, the guest can't be in HLT, and if KVM is querying IRQ blocking for injection, then KVM would need to force an immediate exit anyways since injecting multiple events is impossible. However, because KVM copies int_state verbatim from vmcb02 to vmcb12, the spurious STI shadow is visible to L1 when running a nested VM, which can trip sanity checks, e.g. in VMware's VMM. Hoist the STI+CLI all the way to C code, as the aforementioned calls to guest_state_{enter,exit}_irqoff() already inform lockdep that IRQs are enabled/disabled, and taking a fault on VMRUN with RFLAGS.IF=1 is already possible. I.e. if there's kernel code that is confused by running with RFLAGS.IF=1, then it's already a problem. In practice, since GIF=0 also blocks NMIs, the only change in exposure to non-KVM code (relative to surrounding VMRUN with STI+CLI) is exception handling code, and except for the kvm_rebooting=1 case, all exception in the core VM-Enter/VM-Exit path are fatal. Use the "raw" variants to enable/disable IRQs to avoid tracing in the "no instrumentation" code; the guest state helpers also take care of tracing IRQ state. Oppurtunstically document why KVM needs to do STI in the first place. Reported-by: Doug Covelli <doug.covelli(a)broadcom.com> Closes: https://lore.kernel.org/all/CADH9ctBs1YPmE4aCfGPNBwA10cA8RuAk2gO7542DjMZgs4… Fixes: f14eec0a3203 ("KVM: SVM: move more vmentry code to assembly") Cc: stable(a)vger.kernel.org Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20250224165442.2338294-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a713c803a3a3..0d299f3f921e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4189,6 +4189,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in guest_state_enter_irqoff(); + /* + * Set RFLAGS.IF prior to VMRUN, as the host's RFLAGS.IF at the time of + * VMRUN controls whether or not physical IRQs are masked (KVM always + * runs with V_INTR_MASKING_MASK). Toggle RFLAGS.IF here to avoid the + * temptation to do STI+VMRUN+CLI, as AMD CPUs bleed the STI shadow + * into guest state if delivery of an event during VMRUN triggers a + * #VMEXIT, and the guest_state transitions already tell lockdep that + * IRQs are being enabled/disabled. Note! GIF=0 for the entirety of + * this path, so IRQs aren't actually unmasked while running host code. + */ + raw_local_irq_enable(); + amd_clear_divider(); if (sev_es_guest(vcpu->kvm)) @@ -4197,6 +4209,8 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in else __svm_vcpu_run(svm, spec_ctrl_intercepted); + raw_local_irq_disable(); + guest_state_exit_irqoff(); } diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S index 2ed80aea3bb1..0c61153b275f 100644 --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -170,12 +170,8 @@ SYM_FUNC_START(__svm_vcpu_run) mov VCPU_RDI(%_ASM_DI), %_ASM_DI /* Enter guest mode */ - sti - 3: vmrun %_ASM_AX 4: - cli - /* Pop @svm to RAX while it's the only available register. */ pop %_ASM_AX @@ -340,12 +336,8 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run) mov KVM_VMCB_pa(%rax), %rax /* Enter guest mode */ - sti - 1: vmrun %rax - -2: cli - +2: /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_VMEXIT

3 months, 1 week

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FAILED: patch "[PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x be45bc4eff33d9a7dae84a2150f242a91a617402 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031023-dodge-ungodly-172a@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From be45bc4eff33d9a7dae84a2150f242a91a617402 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Mon, 24 Feb 2025 08:54:41 -0800 Subject: [PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow Enable/disable local IRQs, i.e. set/clear RFLAGS.IF, in the common svm_vcpu_enter_exit() just after/before guest_state_{enter,exit}_irqoff() so that VMRUN is not executed in an STI shadow. AMD CPUs have a quirk (some would say "bug"), where the STI shadow bleeds into the guest's intr_state field if a #VMEXIT occurs during injection of an event, i.e. if the VMRUN doesn't complete before the subsequent #VMEXIT. The spurious "interrupts masked" state is relatively benign, as it only occurs during event injection and is transient. Because KVM is already injecting an event, the guest can't be in HLT, and if KVM is querying IRQ blocking for injection, then KVM would need to force an immediate exit anyways since injecting multiple events is impossible. However, because KVM copies int_state verbatim from vmcb02 to vmcb12, the spurious STI shadow is visible to L1 when running a nested VM, which can trip sanity checks, e.g. in VMware's VMM. Hoist the STI+CLI all the way to C code, as the aforementioned calls to guest_state_{enter,exit}_irqoff() already inform lockdep that IRQs are enabled/disabled, and taking a fault on VMRUN with RFLAGS.IF=1 is already possible. I.e. if there's kernel code that is confused by running with RFLAGS.IF=1, then it's already a problem. In practice, since GIF=0 also blocks NMIs, the only change in exposure to non-KVM code (relative to surrounding VMRUN with STI+CLI) is exception handling code, and except for the kvm_rebooting=1 case, all exception in the core VM-Enter/VM-Exit path are fatal. Use the "raw" variants to enable/disable IRQs to avoid tracing in the "no instrumentation" code; the guest state helpers also take care of tracing IRQ state. Oppurtunstically document why KVM needs to do STI in the first place. Reported-by: Doug Covelli <doug.covelli(a)broadcom.com> Closes: https://lore.kernel.org/all/CADH9ctBs1YPmE4aCfGPNBwA10cA8RuAk2gO7542DjMZgs4… Fixes: f14eec0a3203 ("KVM: SVM: move more vmentry code to assembly") Cc: stable(a)vger.kernel.org Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20250224165442.2338294-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a713c803a3a3..0d299f3f921e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4189,6 +4189,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in guest_state_enter_irqoff(); + /* + * Set RFLAGS.IF prior to VMRUN, as the host's RFLAGS.IF at the time of + * VMRUN controls whether or not physical IRQs are masked (KVM always + * runs with V_INTR_MASKING_MASK). Toggle RFLAGS.IF here to avoid the + * temptation to do STI+VMRUN+CLI, as AMD CPUs bleed the STI shadow + * into guest state if delivery of an event during VMRUN triggers a + * #VMEXIT, and the guest_state transitions already tell lockdep that + * IRQs are being enabled/disabled. Note! GIF=0 for the entirety of + * this path, so IRQs aren't actually unmasked while running host code. + */ + raw_local_irq_enable(); + amd_clear_divider(); if (sev_es_guest(vcpu->kvm)) @@ -4197,6 +4209,8 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in else __svm_vcpu_run(svm, spec_ctrl_intercepted); + raw_local_irq_disable(); + guest_state_exit_irqoff(); } diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S index 2ed80aea3bb1..0c61153b275f 100644 --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -170,12 +170,8 @@ SYM_FUNC_START(__svm_vcpu_run) mov VCPU_RDI(%_ASM_DI), %_ASM_DI /* Enter guest mode */ - sti - 3: vmrun %_ASM_AX 4: - cli - /* Pop @svm to RAX while it's the only available register. */ pop %_ASM_AX @@ -340,12 +336,8 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run) mov KVM_VMCB_pa(%rax), %rax /* Enter guest mode */ - sti - 1: vmrun %rax - -2: cli - +2: /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_VMEXIT

3 months, 1 week

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FAILED: patch "[PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-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>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x be45bc4eff33d9a7dae84a2150f242a91a617402 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025031022-debunk-winner-e8fe@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From be45bc4eff33d9a7dae84a2150f242a91a617402 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Mon, 24 Feb 2025 08:54:41 -0800 Subject: [PATCH] KVM: SVM: Set RFLAGS.IF=1 in C code, to get VMRUN out of the STI shadow Enable/disable local IRQs, i.e. set/clear RFLAGS.IF, in the common svm_vcpu_enter_exit() just after/before guest_state_{enter,exit}_irqoff() so that VMRUN is not executed in an STI shadow. AMD CPUs have a quirk (some would say "bug"), where the STI shadow bleeds into the guest's intr_state field if a #VMEXIT occurs during injection of an event, i.e. if the VMRUN doesn't complete before the subsequent #VMEXIT. The spurious "interrupts masked" state is relatively benign, as it only occurs during event injection and is transient. Because KVM is already injecting an event, the guest can't be in HLT, and if KVM is querying IRQ blocking for injection, then KVM would need to force an immediate exit anyways since injecting multiple events is impossible. However, because KVM copies int_state verbatim from vmcb02 to vmcb12, the spurious STI shadow is visible to L1 when running a nested VM, which can trip sanity checks, e.g. in VMware's VMM. Hoist the STI+CLI all the way to C code, as the aforementioned calls to guest_state_{enter,exit}_irqoff() already inform lockdep that IRQs are enabled/disabled, and taking a fault on VMRUN with RFLAGS.IF=1 is already possible. I.e. if there's kernel code that is confused by running with RFLAGS.IF=1, then it's already a problem. In practice, since GIF=0 also blocks NMIs, the only change in exposure to non-KVM code (relative to surrounding VMRUN with STI+CLI) is exception handling code, and except for the kvm_rebooting=1 case, all exception in the core VM-Enter/VM-Exit path are fatal. Use the "raw" variants to enable/disable IRQs to avoid tracing in the "no instrumentation" code; the guest state helpers also take care of tracing IRQ state. Oppurtunstically document why KVM needs to do STI in the first place. Reported-by: Doug Covelli <doug.covelli(a)broadcom.com> Closes: https://lore.kernel.org/all/CADH9ctBs1YPmE4aCfGPNBwA10cA8RuAk2gO7542DjMZgs4… Fixes: f14eec0a3203 ("KVM: SVM: move more vmentry code to assembly") Cc: stable(a)vger.kernel.org Reviewed-by: Jim Mattson <jmattson(a)google.com> Link: https://lore.kernel.org/r/20250224165442.2338294-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a713c803a3a3..0d299f3f921e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4189,6 +4189,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in guest_state_enter_irqoff(); + /* + * Set RFLAGS.IF prior to VMRUN, as the host's RFLAGS.IF at the time of + * VMRUN controls whether or not physical IRQs are masked (KVM always + * runs with V_INTR_MASKING_MASK). Toggle RFLAGS.IF here to avoid the + * temptation to do STI+VMRUN+CLI, as AMD CPUs bleed the STI shadow + * into guest state if delivery of an event during VMRUN triggers a + * #VMEXIT, and the guest_state transitions already tell lockdep that + * IRQs are being enabled/disabled. Note! GIF=0 for the entirety of + * this path, so IRQs aren't actually unmasked while running host code. + */ + raw_local_irq_enable(); + amd_clear_divider(); if (sev_es_guest(vcpu->kvm)) @@ -4197,6 +4209,8 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in else __svm_vcpu_run(svm, spec_ctrl_intercepted); + raw_local_irq_disable(); + guest_state_exit_irqoff(); } diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S index 2ed80aea3bb1..0c61153b275f 100644 --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -170,12 +170,8 @@ SYM_FUNC_START(__svm_vcpu_run) mov VCPU_RDI(%_ASM_DI), %_ASM_DI /* Enter guest mode */ - sti - 3: vmrun %_ASM_AX 4: - cli - /* Pop @svm to RAX while it's the only available register. */ pop %_ASM_AX @@ -340,12 +336,8 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run) mov KVM_VMCB_pa(%rax), %rax /* Enter guest mode */ - sti - 1: vmrun %rax - -2: cli - +2: /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_VMEXIT

3 months, 1 week

1
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[PATCH v2 0/2] R-Car CANFD fixes

by Biju Das

This patch series addresses 2 issues 1) Fix typo in pattern properties for R-Car V4M. 2) Fix page entries in the AFL list. v1->v2: * Split fixes patches as separate series. * Added Rb tag from Geert for binding patch. * Added the tag Cc:stable@vger.kernel.org Biju Das (2): dt-bindings: can: renesas,rcar-canfd: Fix typo in pattern properties for R-Car V4M can: rcar_canfd: Fix page entries in the AFL list .../bindings/net/can/renesas,rcar-canfd.yaml | 2 +- drivers/net/can/rcar/rcar_canfd.c | 17 ++++++++++------- 2 files changed, 11 insertions(+), 8 deletions(-) -- 2.43.0

3 months, 1 week

4
15
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[PATCH V3] drm/sched: Fix fence reference count leak

by Qianyi Liu

From: qianyi liu <liuqianyi125(a)gmail.com> The last_scheduled fence leaked when an entity was being killed and adding its callback failed. Decrement the reference count of prev when dma_fence_add_callback() fails, ensuring proper balance. Cc: stable(a)vger.kernel.org Fixes: 2fdb8a8f07c2 ("drm/scheduler: rework entity flush, kill and fini") Signed-off-by: qianyi liu <liuqianyi125(a)gmail.com> --- v2 -> v3: Rework commit message (Markus) v1 -> v2: Added 'Fixes:' tag and clarified commit message (Philipp and Matthew) --- drivers/gpu/drm/scheduler/sched_entity.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 69bcf0e99d57..1c0c14bcf726 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -259,9 +259,12 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity) struct drm_sched_fence *s_fence = job->s_fence; dma_fence_get(&s_fence->finished); - if (!prev || dma_fence_add_callback(prev, &job->finish_cb, - drm_sched_entity_kill_jobs_cb)) + if (!prev || + dma_fence_add_callback(prev, &job->finish_cb, + drm_sched_entity_kill_jobs_cb)) { + dma_fence_put(prev); drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb); + } prev = &s_fence->finished; } -- 2.25.1

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