kernel.git/arch/x86, branch linux-6.15.y

KVM: x86: Convert vcpu_run()'s immediate exit param into a generic bitmap

2025-08-20T16:36:34Z

commit 2478b1b220c49d25cb1c3f061ec4f9b351d9a131 upstream. Convert kvm_x86_ops.vcpu_run()'s "force_immediate_exit" boolean parameter into an a generic bitmap so that similar "take action" information can be passed to vendor code without creating a pile of boolean parameters. This will allow dropping kvm_x86_ops.set_dr6() in favor of a new flag, and will also allow for adding similar functionality for re-loading debugctl in the active VMCS. Opportunistically massage the TDX WARN and comment to prepare for adding more run_flags, all of which are expected to be mutually exclusive with TDX, i.e. should be WARNed on. No functional change intended. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-3-seanjc@google.com Signed-off-by: Sean Christopherson [ Removed TDX-specific changes ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with getter/setter APIs

2025-08-20T16:36:34Z

commit 7d0cce6cbe71af6e9c1831bff101a2b9c249c4a2 upstream. Introduce vmx_guest_debugctl_{read,write}() to handle all accesses to vmcs.GUEST_IA32_DEBUGCTL. This will allow stuffing FREEZE_IN_SMM into GUEST_IA32_DEBUGCTL based on the host setting without bleeding the state into the guest, and without needing to copy+paste the FREEZE_IN_SMM logic into every patch that accesses GUEST_IA32_DEBUGCTL. No functional change intended. Cc: stable@vger.kernel.org Signed-off-by: Maxim Levitsky [sean: massage changelog, make inline, use in all prepare_vmcs02() cases] Reviewed-by: Dapeng Mi Link: https://lore.kernel.org/r/20250610232010.162191-8-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter

2025-08-20T16:36:34Z

commit 095686e6fcb4150f0a55b1a25987fad3d8af58d6 upstream. Add a consistency check for L2's guest_ia32_debugctl, as KVM only supports a subset of hardware functionality, i.e. KVM can't rely on hardware to detect illegal/unsupported values. Failure to check the vmcs12 value would allow the guest to load any harware-supported value while running L2. Take care to exempt BTF and LBR from the validity check in order to match KVM's behavior for writes via WRMSR, but without clobbering vmcs12. Even if VM_EXIT_SAVE_DEBUG_CONTROLS is set in vmcs12, L1 can reasonably expect that vmcs12->guest_ia32_debugctl will not be modified if writes to the MSR are being intercepted. Arguably, KVM _should_ update vmcs12 if VM_EXIT_SAVE_DEBUG_CONTROLS is set *and* writes to MSR_IA32_DEBUGCTLMSR are not being intercepted by L1, but that would incur non-trivial complexity and wouldn't change the fact that KVM's handling of DEBUGCTL is blatantly broken. I.e. the extra complexity is not worth carrying. Cc: stable@vger.kernel.org Signed-off-by: Maxim Levitsky Co-developed-by: Sean Christopherson Link: https://lore.kernel.org/r/20250610232010.162191-7-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: VMX: Extract checking of guest's DEBUGCTL into helper

2025-08-20T16:36:34Z

commit 8a4351ac302cd8c19729ba2636acfd0467c22ae8 upstream. Move VMX's logic to check DEBUGCTL values into a standalone helper so that the code can be used by nested VM-Enter to apply the same logic to the value being loaded from vmcs12. KVM needs to explicitly check vmcs12->guest_ia32_debugctl on nested VM-Enter, as hardware may support features that KVM does not, i.e. relying on hardware to detect invalid guest state will result in false negatives. Unfortunately, that means applying KVM's funky suppression of BTF and LBR to vmcs12 so as not to break existing guests. No functional change intended. Reviewed-by: Dapeng Mi Link: https://lore.kernel.org/r/20250610232010.162191-6-seanjc@google.com Signed-off-by: Sean Christopherson Stable-dep-of: 095686e6fcb4 ("KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

x86/bugs: Avoid warning when overriding return thunk

2025-08-20T16:35:58Z

[ Upstream commit 9f85fdb9fc5a1bd308a10a0a7d7e34f2712ba58b ] The purpose of the warning is to prevent an unexpected change to the return thunk mitigation. However, there are legitimate cases where the return thunk is intentionally set more than once. For example, ITS and SRSO both can set the return thunk after retbleed has set it. In both the cases retbleed is still mitigated. Replace the warning with an info about the active return thunk. Suggested-by: Borislav Petkov Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250611-eibrs-fix-v4-3-5ff86cac6c61@linux.intel.com Signed-off-by: Sasha Levin

KVM: VMX: Allow guest to set DEBUGCTL.RTM_DEBUG if RTM is supported

2025-08-15T10:17:07Z

commit 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 upstream. Let the guest set DEBUGCTL.RTM_DEBUG if RTM is supported according to the guest CPUID model, as debug support is supposed to be available if RTM is supported, and there are no known downsides to letting the guest debug RTM aborts. Note, there are no known bug reports related to RTM_DEBUG, the primary motivation is to reduce the probability of breaking existing guests when a future change adds a missing consistency check on vmcs12.GUEST_DEBUGCTL (KVM currently lets L2 run with whatever hardware supports; whoops). Note #2, KVM already emulates DR6.RTM, and doesn't restrict access to DR7.RTM. Fixes: 83c529151ab0 ("KVM: x86: expose Intel cpu new features (HLE, RTM) to guest") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-5-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman

x86/fpu: Delay instruction pointer fixup until after warning

2025-08-15T10:17:07Z

commit 1cec9ac2d071cfd2da562241aab0ef701355762a upstream. Right now, if XRSTOR fails a console message like this is be printed: Bad FPU state detected at restore_fpregs_from_fpstate+0x9a/0x170, reinitializing FPU registers. However, the text location (...+0x9a in this case) is the instruction *AFTER* the XRSTOR. The highlighted instruction in the "Code:" dump also points one instruction late. The reason is that the "fixup" moves RIP up to pass the bad XRSTOR and keep on running after returning from the #GP handler. But it does this fixup before warning. The resulting warning output is nonsensical because it looks like the non-FPU-related instruction is #GP'ing. Do not fix up RIP until after printing the warning. Do this by using the more generic and standard ex_handler_default(). Fixes: d5c8028b4788 ("x86/fpu: Reinitialize FPU registers if restoring FPU state fails") Signed-off-by: Dave Hansen Reviewed-by: Chao Gao Acked-by: Alison Schofield Acked-by: Peter Zijlstra (Intel) Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250624210148.97126F9E%40davehans-spike.ostc.intel.com Signed-off-by: Greg Kroah-Hartman

x86/sev: Evict cache lines during SNP memory validation

2025-08-15T10:17:06Z

Commit 7b306dfa326f70114312b320d083b21fa9481e1e upstream. An SNP cache coherency vulnerability requires a cache line eviction mitigation when validating memory after a page state change to private. The specific mitigation is to touch the first and last byte of each 4K page that is being validated. There is no need to perform the mitigation when performing a page state change to shared and rescinding validation. CPUID bit Fn8000001F_EBX[31] defines the COHERENCY_SFW_NO CPUID bit that, when set, indicates that the software mitigation for this vulnerability is not needed. Implement the mitigation and invoke it when validating memory (making it private) and the COHERENCY_SFW_NO bit is not set, indicating the SNP guest is vulnerable. Co-developed-by: Michael Roth Signed-off-by: Michael Roth Signed-off-by: Tom Lendacky Signed-off-by: Borislav Petkov (AMD) Acked-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

x86/irq: Plug vector setup race

2025-08-15T10:17:00Z

[ Upstream commit ce0b5eedcb753697d43f61dd2e27d68eb5d3150f ] Hogan reported a vector setup race, which overwrites the interrupt descriptor in the per CPU vector array resulting in a disfunctional device. CPU0 CPU1 interrupt is raised in APIC IRR but not handled free_irq() per_cpu(vector_irq, CPU1)[vector] = VECTOR_SHUTDOWN; request_irq() common_interrupt() d = this_cpu_read(vector_irq[vector]); per_cpu(vector_irq, CPU1)[vector] = desc; if (d == VECTOR_SHUTDOWN) this_cpu_write(vector_irq[vector], VECTOR_UNUSED); free_irq() cannot observe the pending vector in the CPU1 APIC as there is no way to query the remote CPUs APIC IRR. This requires that request_irq() uses the same vector/CPU as the one which was freed, but this also can be triggered by a spurious interrupt. Interestingly enough this problem managed to be hidden for more than a decade. Prevent this by reevaluating vector_irq under the vector lock, which is held by the interrupt activation code when vector_irq is updated. To avoid ifdeffery or IS_ENABLED() nonsense, move the [un]lock_vector_lock() declarations out under the CONFIG_IRQ_DOMAIN_HIERARCHY guard as it's only provided when CONFIG_X86_LOCAL_APIC=y. The current CONFIG_IRQ_DOMAIN_HIERARCHY guard is selected by CONFIG_X86_LOCAL_APIC, but can also be selected by other parts of the Kconfig system, which makes 32-bit UP builds with CONFIG_X86_LOCAL_APIC=n fail. Can we just get rid of this !APIC nonsense once and forever? Fixes: 9345005f4eed ("x86/irq: Fix do_IRQ() interrupt warning for cpu hotplug retriggered irqs") Reported-by: Hogan Wang Signed-off-by: Thomas Gleixner Tested-by: Hogan Wang Link: https://lore.kernel.org/all/draft-87ikjhrhhh.ffs@tglx Signed-off-by: Sasha Levin

x86/hyperv: Fix usage of cpu_online_mask to get valid cpu

2025-08-01T08:51:24Z

[ Upstream commit bb169f80ed5a156ec3405e0e49c6b8e9ae264718 ] Accessing cpu_online_mask here is problematic because the cpus read lock is not held in this context. However, cpu_online_mask isn't needed here since the effective affinity mask is guaranteed to be valid in this callback. So, just use cpumask_first() to get the cpu instead of ANDing it with cpus_online_mask unnecessarily. Fixes: e39397d1fd68 ("x86/hyperv: implement an MSI domain for root partition") Reported-by: Michael Kelley Closes: https://lore.kernel.org/linux-hyperv/SN6PR02MB4157639630F8AD2D8FD8F52FD475A@SN6PR02MB4157.namprd02.prod.outlook.com/ Suggested-by: Thomas Gleixner Signed-off-by: Nuno Das Neves Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1751582677-30930-4-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1751582677-30930-4-git-send-email-nunodasneves@linux.microsoft.com> Signed-off-by: Sasha Levin