kernel/arch/x86/hypervisor/guest.cpp

// Copyright 2017 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include <arch/x86/apic.h>
#include <arch/x86/feature.h>
#include <zircon/syscalls/hypervisor.h>

#include "vmx_cpu_state_priv.h"

static void ignore_msr(VmxPage* msr_bitmaps_page, bool ignore_writes, uint32_t msr) {
    // From Volume 3, Section 24.6.9.
    uint8_t* msr_bitmaps = msr_bitmaps_page->VirtualAddress<uint8_t>();
    if (msr >= 0xc0000000) {
        msr_bitmaps += 1 << 10;
    }

    uint16_t msr_low = msr & 0x1fff;
    uint16_t msr_byte = msr_low / 8;
    uint8_t msr_bit = msr_low % 8;

    // Ignore reads to the MSR.
    msr_bitmaps[msr_byte] &= (uint8_t) ~(1 << msr_bit);

    if (ignore_writes) {
        // Ignore writes to the MSR.
        msr_bitmaps += 2 << 10;
        msr_bitmaps[msr_byte] &= (uint8_t) ~(1 << msr_bit);
    }
}

// static
zx_status_t Guest::Create(ktl::unique_ptr<Guest>* out) {
    // Check that the CPU supports VMX.
    if (!x86_feature_test(X86_FEATURE_VMX)) {
        return ZX_ERR_NOT_SUPPORTED;
    }

    zx_status_t status = alloc_vmx_state();
    if (status != ZX_OK) {
        return status;
    }

    fbl::AllocChecker ac;
    ktl::unique_ptr<Guest> guest(new (&ac) Guest);
    if (!ac.check()) {
        return ZX_ERR_NO_MEMORY;
    }

    status = hypervisor::GuestPhysicalAddressSpace::Create(&guest->gpas_);
    if (status != ZX_OK) {
        return status;
    }

    // Setup common MSR bitmaps.
    VmxInfo vmx_info;
    status = guest->msr_bitmaps_page_.Alloc(vmx_info, UINT8_MAX);
    if (status != ZX_OK) {
        return status;
    }

    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_PAT);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_EFER);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_FS_BASE);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_GS_BASE);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_KERNEL_GS_BASE);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_STAR);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_LSTAR);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_FMASK);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_TSC_ADJUST);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_TSC_AUX);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_SYSENTER_CS);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_SYSENTER_ESP);
    ignore_msr(&guest->msr_bitmaps_page_, true, X86_MSR_IA32_SYSENTER_EIP);

    // Setup VPID allocator
    fbl::AutoLock lock(&guest->vcpu_mutex_);
    status = guest->vpid_allocator_.Init();
    if (status != ZX_OK) {
        return status;
    }

    *out = ktl::move(guest);
    return ZX_OK;
}

Guest::~Guest() {
    free_vmx_state();
}

zx_status_t Guest::SetTrap(uint32_t kind, zx_vaddr_t addr, size_t len,
                           fbl::RefPtr<PortDispatcher> port, uint64_t key) {
    if (len == 0) {
        return ZX_ERR_INVALID_ARGS;
    } else if (SIZE_MAX - len < addr) {
        return ZX_ERR_OUT_OF_RANGE;
    }

    switch (kind) {
    case ZX_GUEST_TRAP_MEM:
        if (port) {
            return ZX_ERR_INVALID_ARGS;
        }
        break;
    case ZX_GUEST_TRAP_BELL:
        if (!port) {
            return ZX_ERR_INVALID_ARGS;
        }
        break;
    case ZX_GUEST_TRAP_IO:
        if (port) {
            return ZX_ERR_INVALID_ARGS;
        } else if (addr + len > UINT16_MAX) {
            return ZX_ERR_OUT_OF_RANGE;
        }
        return traps_.InsertTrap(kind, addr, len, ktl::move(port), key);
    default:
        return ZX_ERR_INVALID_ARGS;
    }

    // Common logic for memory-based traps.
    if (!IS_PAGE_ALIGNED(addr) || !IS_PAGE_ALIGNED(len)) {
        return ZX_ERR_INVALID_ARGS;
    }
    zx_status_t status = gpas_->UnmapRange(addr, len);
    if (status != ZX_OK) {
        return status;
    }
    return traps_.InsertTrap(kind, addr, len, ktl::move(port), key);
}

zx_status_t Guest::AllocVpid(uint16_t* vpid) {
    fbl::AutoLock lock(&vcpu_mutex_);
    return vpid_allocator_.AllocId(vpid);
}

zx_status_t Guest::FreeVpid(uint16_t vpid) {
    fbl::AutoLock lock(&vcpu_mutex_);
    return vpid_allocator_.FreeId(vpid);
}