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linux/arch/x86/kvm/xen.h
David Woodhouse 8e62bf2bfa KVM: x86/xen: inject vCPU upcall vector when local APIC is enabled 
Linux guests since commit b1c3497e60 ("x86/xen: Add support for
HVMOP_set_evtchn_upcall_vector") in v6.0 onwards will use the per-vCPU
upcall vector when it's advertised in the Xen CPUID leaves.

This upcall is injected through the guest's local APIC as an MSI, unlike
the older system vector which was merely injected by the hypervisor any
time the CPU was able to receive an interrupt and the upcall_pending
flags is set in its vcpu_info.

Effectively, that makes the per-CPU upcall edge triggered instead of
level triggered, which results in the upcall being lost if the MSI is
delivered when the local APIC is *disabled*.

Xen checks the vcpu_info->evtchn_upcall_pending flag when the local APIC
for a vCPU is software enabled (in fact, on any write to the SPIV
register which doesn't disable the APIC). Do the same in KVM since KVM
doesn't provide a way for userspace to intervene and trap accesses to
the SPIV register of a local APIC emulated by KVM.

Fixes: fde0451be8 ("KVM: x86/xen: Support per-vCPU event channel upcall via local APIC")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240227115648.3104-3-dwmw2@infradead.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-03-04 16:22:36 -08:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright © 2019 Oracle and/or its affiliates. All rights reserved.
* Copyright © 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* KVM Xen emulation
*/
#ifndef __ARCH_X86_KVM_XEN_H__
#define __ARCH_X86_KVM_XEN_H__
#include <asm/xen/hypervisor.h>
#ifdef CONFIG_KVM_XEN
#include <linux/jump_label_ratelimit.h>
extern struct static_key_false_deferred kvm_xen_enabled;
int __kvm_xen_has_interrupt(struct kvm_vcpu *vcpu);
void kvm_xen_inject_pending_events(struct kvm_vcpu *vcpu);
void kvm_xen_inject_vcpu_vector(struct kvm_vcpu *vcpu);
int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data);
int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data);
int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);
int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data);
int kvm_xen_hvm_evtchn_send(struct kvm *kvm, struct kvm_irq_routing_xen_evtchn *evt);
int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data);
int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc);
void kvm_xen_init_vm(struct kvm *kvm);
void kvm_xen_destroy_vm(struct kvm *kvm);
void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu);
void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu);
int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe,
struct kvm *kvm);
int kvm_xen_setup_evtchn(struct kvm *kvm,
struct kvm_kernel_irq_routing_entry *e,
const struct kvm_irq_routing_entry *ue);
void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu);
static inline void kvm_xen_sw_enable_lapic(struct kvm_vcpu *vcpu)
{
/*
* The local APIC is being enabled. If the per-vCPU upcall vector is
* set and the vCPU's evtchn_upcall_pending flag is set, inject the
* interrupt.
*/
if (static_branch_unlikely(&kvm_xen_enabled.key) &&
vcpu->arch.xen.vcpu_info_cache.active &&
vcpu->arch.xen.upcall_vector && __kvm_xen_has_interrupt(vcpu))
kvm_xen_inject_vcpu_vector(vcpu);
}
static inline bool kvm_xen_msr_enabled(struct kvm *kvm)
{
return static_branch_unlikely(&kvm_xen_enabled.key) &&
kvm->arch.xen_hvm_config.msr;
}
static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
{
return static_branch_unlikely(&kvm_xen_enabled.key) &&
(kvm->arch.xen_hvm_config.flags &
KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL);
}
static inline int kvm_xen_has_interrupt(struct kvm_vcpu *vcpu)
{
if (static_branch_unlikely(&kvm_xen_enabled.key) &&
vcpu->arch.xen.vcpu_info_cache.active &&
vcpu->kvm->arch.xen.upcall_vector)
return __kvm_xen_has_interrupt(vcpu);
return 0;
}
static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu)
{
return static_branch_unlikely(&kvm_xen_enabled.key) &&
vcpu->arch.xen.evtchn_pending_sel;
}
static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu)
{
return !!vcpu->arch.xen.timer_virq;
}
static inline int kvm_xen_has_pending_timer(struct kvm_vcpu *vcpu)
{
if (kvm_xen_hypercall_enabled(vcpu->kvm) && kvm_xen_timer_enabled(vcpu))
return atomic_read(&vcpu->arch.xen.timer_pending);
return 0;
}
void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu);
#else
static inline int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
{
return 1;
}
static inline void kvm_xen_init_vm(struct kvm *kvm)
{
}
static inline void kvm_xen_destroy_vm(struct kvm *kvm)
{
}
static inline void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu)
{
}
static inline void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
{
}
static inline void kvm_xen_sw_enable_lapic(struct kvm_vcpu *vcpu)
{
}
static inline bool kvm_xen_msr_enabled(struct kvm *kvm)
{
return false;
}
static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
{
return false;
}
static inline int kvm_xen_has_interrupt(struct kvm_vcpu *vcpu)
{
return 0;
}
static inline void kvm_xen_inject_pending_events(struct kvm_vcpu *vcpu)
{
}
static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu)
{
return false;
}
static inline int kvm_xen_has_pending_timer(struct kvm_vcpu *vcpu)
{
return 0;
}
static inline void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu)
{
}
static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu)
{
return false;
}
static inline void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu)
{
}
#endif
int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
#include <asm/pvclock-abi.h>
#include <asm/xen/interface.h>
#include <xen/interface/vcpu.h>
void kvm_xen_update_runstate(struct kvm_vcpu *vcpu, int state);
static inline void kvm_xen_runstate_set_running(struct kvm_vcpu *vcpu)
{
kvm_xen_update_runstate(vcpu, RUNSTATE_running);
}
static inline void kvm_xen_runstate_set_preempted(struct kvm_vcpu *vcpu)
{
/*
* If the vCPU wasn't preempted but took a normal exit for
* some reason (hypercalls, I/O, etc.), that is accounted as
* still RUNSTATE_running, as the VMM is still operating on
* behalf of the vCPU. Only if the VMM does actually block
* does it need to enter RUNSTATE_blocked.
*/
if (WARN_ON_ONCE(!vcpu->preempted))
return;
kvm_xen_update_runstate(vcpu, RUNSTATE_runnable);
}
/* 32-bit compatibility definitions, also used natively in 32-bit build */
struct compat_arch_vcpu_info {
unsigned int cr2;
unsigned int pad[5];
};
struct compat_vcpu_info {
uint8_t evtchn_upcall_pending;
uint8_t evtchn_upcall_mask;
uint16_t pad;
uint32_t evtchn_pending_sel;
struct compat_arch_vcpu_info arch;
struct pvclock_vcpu_time_info time;
}; /* 64 bytes (x86) */
struct compat_arch_shared_info {
unsigned int max_pfn;
unsigned int pfn_to_mfn_frame_list_list;
unsigned int nmi_reason;
unsigned int p2m_cr3;
unsigned int p2m_vaddr;
unsigned int p2m_generation;
uint32_t wc_sec_hi;
};
struct compat_shared_info {
struct compat_vcpu_info vcpu_info[MAX_VIRT_CPUS];
uint32_t evtchn_pending[32];
uint32_t evtchn_mask[32];
struct pvclock_wall_clock wc;
struct compat_arch_shared_info arch;
};
#define COMPAT_EVTCHN_2L_NR_CHANNELS (8 * \
sizeof_field(struct compat_shared_info, \
evtchn_pending))
struct compat_vcpu_runstate_info {
int state;
uint64_t state_entry_time;
uint64_t time[4];
} __attribute__((packed));
struct compat_sched_poll {
/* This is actually a guest virtual address which points to ports. */
uint32_t ports;
unsigned int nr_ports;
uint64_t timeout;
};
#endif /* __ARCH_X86_KVM_XEN_H__ */
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