Differential D30006 Diff 120316 sys/x86/xen/xen_arch_intr.c

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sys/x86/xen/xen_arch_intr.c

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				/*-
				* SPDX-License-Identifier: MIT OR GPL-2.0-only
				*
				* Copyright © 2013 Spectra Logic Corporation
				* Copyright © 2018 John Baldwin/The FreeBSD Foundation
				* Copyright © 2019 Roger Pau Monné/Citrix Systems R&D
				* Copyright © 2021 Elliott Mitchell
				*
				* This file may be distributed separately from the Linux kernel, or
				* incorporated into other software packages, subject to the following license:
				*
				* Permission is hereby granted, free of charge, to any person obtaining a copy
				* of this source file (the "Software"), to deal in the Software without
				* restriction, including without limitation the rights to use, copy, modify,
				* merge, publish, distribute, sublicense, and/or sell copies of the Software,
				* and to permit persons to whom the Software is furnished to do so, subject to
				* the following conditions:
				*
				* The above copyright notice and this permission notice shall be included in
				* all copies or substantial portions of the Software.
				*
				* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
				* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
				* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
				* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
				* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
				* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
				* IN THE SOFTWARE.
				*/

				#include <sys/cdefs.h>
				__FBSDID("$FreeBSD$");

				#include <sys/param.h>
				#include <sys/bus.h>
				#include <sys/kernel.h>
				#include <sys/pcpu.h>
				#include <sys/proc.h>
				#include <sys/smp.h>
				#include <sys/stddef.h>

				#include <xen/xen-os.h>
				#include <xen/xen_intr.h>

				#include <x86/intr_machdep.h>
				#include <x86/apicvar.h>

				/********************** Xen x86 interrupt interface **********************/

				/*
				* Pointers to the interrupt counters
				*/
				DPCPU_DEFINE_STATIC(u_long *, pintrcnt);

				static void
				xen_intrcnt_init(void *dummy __unused)
				{
				unsigned int i;

				if (!xen_domain())
				return;

				CPU_FOREACH(i) {
				char buf[MAXCOMLEN + 1];

				snprintf(buf, sizeof(buf), "cpu%d:xen", i);
				intrcnt_add(buf, DPCPU_ID_PTR(i, pintrcnt));
				}
				}
				SYSINIT(xen_intrcnt_init, SI_SUB_INTR, SI_ORDER_MIDDLE, xen_intrcnt_init, NULL);

				/*
				* Transition from assembly language, called from
				* sys/{amd64/amd64\|i386/i386}/apic_vector.S
				*/
				extern void xen_arch_intr_handle_upcall(struct trapframe *);
				void
				xen_arch_intr_handle_upcall(struct trapframe *trap_frame)
				{
				struct trapframe *old;

				/*
				* Disable preemption in order to always check and fire events
				* on the right vCPU
				*/
				ehem_freebsd_m5p.comAuthorUnsubmitted Done Inline Actions Approach #2 is here set `curthread->td_intr_frame = trap_frame;` (which is passed from assembly language). Then after the call set `curthread->td_intr_frame = NULL;`. I think this is right, but I would need a review... ehem_freebsd_m5p.com: Approach #2 is here set `curthread->td_intr_frame = trap_frame;` (which is passed from…
				mhorneUnsubmitted Done Inline Actions Yep, agreed that this is where you ought to set it. But as I said, you need to save and restore the previous value of `td_intr_frame`, not set it to `NULL`. mhorne: Yep, agreed that this is where you ought to set it. But as I said, you need to save and restore…
				ehem_freebsd_m5p.comAuthorUnsubmitted Done Inline Actions Okay, I can believe that. I cringe at how this means it will be saved both here and in `intr_event_handle()`, but that could well be correct. I was thinking setting it to `NULL` might be correct at this point the interrupt is returning and there shouldn't be further trap frames on the stack. ehem_freebsd_m5p.com: Okay, I can believe that. I cringe at how this means it will be saved both here and in…
				critical_enter();

				ehem_freebsd_m5p.comAuthorUnsubmitted Done Inline Actions I'm now guessing this (and the decrement 7 lines below) shouldn't be done. I'm not familiar enough with this to confidently make the call and need advice for whether this is correct. ehem_freebsd_m5p.com: I'm now guessing this (and the decrement 7 lines below) shouldn't be done. I'm not familiar…
				++*DPCPU_GET(pintrcnt);

				++curthread->td_intr_nesting_level;
				old = curthread->td_intr_frame;
				curthread->td_intr_frame = trap_frame;

				xen_intr_handle_upcall(NULL);

				curthread->td_intr_frame = old;
				--curthread->td_intr_nesting_level;
				ehem_freebsd_m5p.comAuthorUnsubmitted Done Inline Actions Note to reviewers (@royger) this is the really significant delta. Previously this would be done if `xen_intr_handle_upcall()` was invoked for the XenPCI code, but now this will only be invoked for the main Xen interrupt vector. This seems likely correct, but is worthy of reviewer attention. ehem_freebsd_m5p.com: Note to reviewers (@royger) this is the really significant delta. Previously this would be…

				if (xen_evtchn_needs_ack)
				lapic_eoi();

				critical_exit();
				}