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5fcc48d521
Vishal reported that KVM unit test 'x2apic' started failing after commit0e98eb1481("entry: Prepare for deferred hrtimer rearming"). The reason is that KVM/VMX is injecting interrupts while it has interrupts disabled, for a context that will enable interrupts, this means that regs->flags.X86_EFLAGS_IF == 0 and irqentry_exit() will not do the right thing. Notably, irqentry_exit() must not call hrtimer_rearm_deferred() when the return context does not have IF set, because this will cause problems vs NMIs. Therefore, fix up the state after the injection. Fixes:0e98eb1481("entry: Prepare for deferred hrtimer rearming") Reported-by: "Verma, Vishal L" <vishal.l.verma@intel.com> Suggested-by: Thomas Gleixner <tglx@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: "Verma, Vishal L" <vishal.l.verma@intel.com> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Zhao Liu <zhao1.liu@intel.com> Tested-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com> Link: https://patch.msgid.link/20260423155936.957351833@infradead.org Closes: https://lore.kernel.org/r/70cd3e97fbb796e2eb2ff8cd4b7614ada05a5f24.camel%40intel.com
62 lines
1.9 KiB
C
62 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/entry-common.h>
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#include <linux/kvm_types.h>
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#include <linux/hrtimer_rearm.h>
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#include <asm/fred.h>
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#include <asm/desc.h>
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#if IS_ENABLED(CONFIG_KVM_INTEL)
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/*
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* On VMX, NMIs and IRQs (as configured by KVM) are acknowledged by hardware as
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* part of the VM-Exit, i.e. the event itself is consumed as part the VM-Exit.
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* x86_entry_from_kvm() is invoked by KVM to effectively forward NMIs and IRQs
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* to the kernel for servicing. On SVM, a.k.a. AMD, the NMI/IRQ VM-Exit is
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* purely a signal that an NMI/IRQ is pending, i.e. the event that triggered
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* the VM-Exit is held pending until it's unblocked in the host.
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*/
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noinstr void x86_entry_from_kvm(unsigned int event_type, unsigned int vector)
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{
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if (event_type == EVENT_TYPE_EXTINT) {
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#ifdef CONFIG_X86_64
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/*
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* Use FRED dispatch, even when running IDT. The dispatch
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* tables are kept in sync between FRED and IDT, and the FRED
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* dispatch works well with CFI.
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*/
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fred_entry_from_kvm(event_type, vector);
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#else
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idt_entry_from_kvm(vector);
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#endif
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/*
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* Strictly speaking, only the NMI path requires noinstr.
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*/
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instrumentation_begin();
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/*
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* KVM/VMX will dispatch from IRQ-disabled but for a context
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* that will have IRQs-enabled. This confuses the entry code
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* and it will not have reprogrammed the timer. Do so now.
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*/
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hrtimer_rearm_deferred();
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instrumentation_end();
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return;
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}
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WARN_ON_ONCE(event_type != EVENT_TYPE_NMI);
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#ifdef CONFIG_X86_64
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if (cpu_feature_enabled(X86_FEATURE_FRED))
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return fred_entry_from_kvm(event_type, vector);
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#endif
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/*
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* Notably, we must use IDT dispatch for NMI when running in IDT mode.
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* The FRED NMI context is significantly different and will not work
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* right (specifically FRED fixed the NMI recursion issue).
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*/
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idt_entry_from_kvm(vector);
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}
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EXPORT_SYMBOL_FOR_KVM(x86_entry_from_kvm);
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#endif
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