vmm_host.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 NetApp, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/pcpu.h>

#include <machine/cpufunc.h>
#include <machine/segments.h>
#include <machine/specialreg.h>

#include "vmm_host.h"

static uint64_t vmm_host_efer, vmm_host_pat, vmm_host_cr0, vmm_host_cr4,
	vmm_host_xcr0;
static struct xsave_limits vmm_xsave_limits;

void
vmm_host_state_init(void)
{
	int regs[4];

	vmm_host_efer = rdmsr(MSR_EFER);
	vmm_host_pat = rdmsr(MSR_PAT);

	/*
	 * We always want CR0.TS to be set when the processor does a VM exit.
	 *
	 * With emulation turned on unconditionally after a VM exit, we are
	 * able to trap inadvertent use of the FPU until the guest FPU state
	 * has been safely squirreled away.
	 */
	vmm_host_cr0 = rcr0() | CR0_TS;

	/*
	 * On non-PCID or PCID but without INVPCID support machines,
	 * we flush kernel i.e. global TLB entries, by temporary
	 * clearing the CR4.PGE bit, see invltlb_glob().  If
	 * preemption occurs at the wrong time, cached vmm_host_cr4
	 * might store the value with CR4.PGE cleared.  Since FreeBSD
	 * requires support for PG_G on amd64, just set it
	 * unconditionally.
	 */
	vmm_host_cr4 = rcr4() | CR4_PGE;

	/*
	 * Only permit a guest to use XSAVE if the host is using
	 * XSAVE.  Only permit a guest to use XSAVE features supported
	 * by the host.  This ensures that the FPU state used by the
	 * guest is always a subset of the saved guest FPU state.
	 *
	 * In addition, only permit known XSAVE features where the
	 * rules for which features depend on other features is known
	 * to properly emulate xsetbv.
	 */
	if (vmm_host_cr4 & CR4_XSAVE) {
		vmm_xsave_limits.xsave_enabled = 1;
		vmm_host_xcr0 = rxcr(0);
		vmm_xsave_limits.xcr0_allowed = vmm_host_xcr0 &
		    (XFEATURE_AVX | XFEATURE_MPX | XFEATURE_AVX512);

		cpuid_count(0xd, 0x0, regs);
		vmm_xsave_limits.xsave_max_size = regs[1];
	}
}

uint64_t
vmm_get_host_pat(void)
{

	return (vmm_host_pat);
}

uint64_t
vmm_get_host_efer(void)
{

	return (vmm_host_efer);
}

uint64_t
vmm_get_host_cr0(void)
{

	return (vmm_host_cr0);
}

uint64_t
vmm_get_host_cr4(void)
{

	return (vmm_host_cr4);
}

uint64_t
vmm_get_host_xcr0(void)
{

	return (vmm_host_xcr0);
}

uint64_t
vmm_get_host_datasel(void)
{

	return (GSEL(GDATA_SEL, SEL_KPL));

}

uint64_t
vmm_get_host_codesel(void)
{

	return (GSEL(GCODE_SEL, SEL_KPL));
}

uint64_t
vmm_get_host_tsssel(void)
{

	return (GSEL(GPROC0_SEL, SEL_KPL));
}

uint64_t
vmm_get_host_fsbase(void)
{

	return (0);
}

uint64_t
vmm_get_host_idtrbase(void)
{

	return (r_idt.rd_base);
}

const struct xsave_limits *
vmm_get_xsave_limits(void)
{

	return (&vmm_xsave_limits);
}