qemu/include/sysemu/kvm_xen.h

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/*
* Xen HVM emulation support in KVM
*
* Copyright © 2019 Oracle and/or its affiliates. All rights reserved.
* Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef QEMU_SYSEMU_KVM_XEN_H
#define QEMU_SYSEMU_KVM_XEN_H
/* The KVM API uses these to indicate "no GPA" or "no GFN" */
#define INVALID_GPA UINT64_MAX
#define INVALID_GFN UINT64_MAX
/* QEMU plays the rôle of dom0 for "interdomain" communication. */
#define DOMID_QEMU 0
int kvm_xen_soft_reset(void);
uint32_t kvm_xen_get_caps(void);
void *kvm_xen_get_vcpu_info_hva(uint32_t vcpu_id);
void kvm_xen_inject_vcpu_callback_vector(uint32_t vcpu_id, int type);
hw/xen: Support HVM_PARAM_CALLBACK_TYPE_GSI callback The GSI callback (and later PCI_INTX) is a level triggered interrupt. It is asserted when an event channel is delivered to vCPU0, and is supposed to be cleared when the vcpu_info->evtchn_upcall_pending field for vCPU0 is cleared again. Thankfully, Xen does *not* assert the GSI if the guest sets its own evtchn_upcall_pending field; we only need to assert the GSI when we have delivered an event for ourselves. So that's the easy part, kind of. There's a slight complexity in that we need to hold the BQL before we can call qemu_set_irq(), and we definitely can't do that while holding our own port_lock (because we'll need to take that from the qemu-side functions that the PV backend drivers will call). So if we end up wanting to set the IRQ in a context where we *don't* already hold the BQL, defer to a BH. However, we *do* need to poll for the evtchn_upcall_pending flag being cleared. In an ideal world we would poll that when the EOI happens on the PIC/IOAPIC. That's how it works in the kernel with the VFIO eventfd pairs — one is used to trigger the interrupt, and the other works in the other direction to 'resample' on EOI, and trigger the first eventfd again if the line is still active. However, QEMU doesn't seem to do that. Even VFIO level interrupts seem to be supported by temporarily unmapping the device's BARs from the guest when an interrupt happens, then trapping *all* MMIO to the device and sending the 'resample' event on *every* MMIO access until the IRQ is cleared! Maybe in future we'll plumb the 'resample' concept through QEMU's irq framework but for now we'll do what Xen itself does: just check the flag on every vmexit if the upcall GSI is known to be asserted. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>
2022-12-15 23:35:24 +03:00
void kvm_xen_set_callback_asserted(void);
int kvm_xen_set_vcpu_virq(uint32_t vcpu_id, uint16_t virq, uint16_t port);
uint16_t kvm_xen_get_gnttab_max_frames(void);
uint16_t kvm_xen_get_evtchn_max_pirq(void);
#define kvm_xen_has_cap(cap) (!!(kvm_xen_get_caps() & \
KVM_XEN_HVM_CONFIG_ ## cap))
#define XEN_SPECIAL_AREA_ADDR 0xfeff8000UL
#define XEN_SPECIAL_AREA_SIZE 0x4000UL
#define XEN_SPECIALPAGE_CONSOLE 0
#define XEN_SPECIALPAGE_XENSTORE 1
#define XEN_SPECIAL_PFN(x) ((XEN_SPECIAL_AREA_ADDR >> TARGET_PAGE_BITS) + \
XEN_SPECIALPAGE_##x)
#endif /* QEMU_SYSEMU_KVM_XEN_H */