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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
*/
#include "x86.h"
#include "xen.h"
#include "hyperv.h"
#include <linux/kvm_host.h>
#include <trace/events/kvm.h>
#include <xen/interface/xen.h>
#include "trace.h"
DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
{
int ret;
int idx = srcu_read_lock(&kvm->srcu);
ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
gfn_to_gpa(gfn), PAGE_SIZE);
if (!ret) {
kvm->arch.xen.shinfo_set = true;
}
srcu_read_unlock(&kvm->srcu, idx);
return ret;
}
int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
{
int r = -ENOENT;
mutex_lock(&kvm->lock);
mutex_unlock(&kvm->lock);
switch (data->type) {
case KVM_XEN_ATTR_TYPE_LONG_MODE:
if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) {
r = -EINVAL;
} else {
kvm->arch.xen.long_mode = !!data->u.long_mode;
r = 0;
}
break;
case KVM_XEN_ATTR_TYPE_SHARED_INFO:
r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
break;
default:
break;
}
mutex_unlock(&kvm->lock);
return r;
}
int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
{
int r = -ENOENT;
mutex_lock(&kvm->lock);
switch (data->type) {
case KVM_XEN_ATTR_TYPE_LONG_MODE:
data->u.long_mode = kvm->arch.xen.long_mode;
r = 0;
break;
case KVM_XEN_ATTR_TYPE_SHARED_INFO:
if (kvm->arch.xen.shinfo_set) {
data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa);
r = 0;
}
break;
default:
break;
}
mutex_unlock(&kvm->lock);
return r;
}
int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
{
struct kvm *kvm = vcpu->kvm;
u32 page_num = data & ~PAGE_MASK;
u64 page_addr = data & PAGE_MASK;
bool lm = is_long_mode(vcpu);
/* Latch long_mode for shared_info pages etc. */
vcpu->kvm->arch.xen.long_mode = lm;
/*
* If Xen hypercall intercept is enabled, fill the hypercall
* page with VMCALL/VMMCALL instructions since that's what
* we catch. Else the VMM has provided the hypercall pages
* with instructions of its own choosing, so use those.
*/
if (kvm_xen_hypercall_enabled(kvm)) {
u8 instructions[32];
int i;
if (page_num)
return 1;
/* mov imm32, %eax */
instructions[0] = 0xb8;
/* vmcall / vmmcall */
kvm_x86_ops.patch_hypercall(vcpu, instructions + 5);
/* ret */
instructions[8] = 0xc3;
/* int3 to pad */
memset(instructions + 9, 0xcc, sizeof(instructions) - 9);
for (i = 0; i < PAGE_SIZE / sizeof(instructions); i++) {
*(u32 *)&instructions[1] = i;
if (kvm_vcpu_write_guest(vcpu,
page_addr + (i * sizeof(instructions)),
instructions, sizeof(instructions)))
return 1;
}
} else {
u64 blob_addr = lm ? kvm->arch.xen_hvm_config.blob_addr_64
: kvm->arch.xen_hvm_config.blob_addr_32;
u8 blob_size = lm ? kvm->arch.xen_hvm_config.blob_size_64
: kvm->arch.xen_hvm_config.blob_size_32;
u8 *page;
if (page_num >= blob_size)
return 1;
blob_addr += page_num * PAGE_SIZE;
page = memdup_user((u8 __user *)blob_addr, PAGE_SIZE);
if (IS_ERR(page))
return PTR_ERR(page);
if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE)) {
kfree(page);
return 1;
}
}
return 0;
}
int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc)
{
if (xhc->flags & ~KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL)
return -EINVAL;
/*
* With hypercall interception the kernel generates its own
* hypercall page so it must not be provided.
*/
if ((xhc->flags & KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL) &&
(xhc->blob_addr_32 || xhc->blob_addr_64 ||
xhc->blob_size_32 || xhc->blob_size_64))
return -EINVAL;
mutex_lock(&kvm->lock);
if (xhc->msr && !kvm->arch.xen_hvm_config.msr)
static_branch_inc(&kvm_xen_enabled.key);
else if (!xhc->msr && kvm->arch.xen_hvm_config.msr)
static_branch_slow_dec_deferred(&kvm_xen_enabled);
memcpy(&kvm->arch.xen_hvm_config, xhc, sizeof(*xhc));
mutex_unlock(&kvm->lock);
return 0;
}
void kvm_xen_destroy_vm(struct kvm *kvm)
{
if (kvm->arch.xen_hvm_config.msr)
static_branch_slow_dec_deferred(&kvm_xen_enabled);
}
static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
{
kvm_rax_write(vcpu, result);
return kvm_skip_emulated_instruction(vcpu);
}
static int kvm_xen_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
{
struct kvm_run *run = vcpu->run;
if (unlikely(!kvm_is_linear_rip(vcpu, vcpu->arch.xen.hypercall_rip)))
return 1;
return kvm_xen_hypercall_set_result(vcpu, run->xen.u.hcall.result);
}
int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
{
bool longmode;
u64 input, params[6];
input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX);
/* Hyper-V hypercalls get bit 31 set in EAX */
if ((input & 0x80000000) &&
kvm_hv_hypercall_enabled(vcpu->kvm))
return kvm_hv_hypercall(vcpu);
longmode = is_64_bit_mode(vcpu);
if (!longmode) {
params[0] = (u32)kvm_rbx_read(vcpu);
params[1] = (u32)kvm_rcx_read(vcpu);
params[2] = (u32)kvm_rdx_read(vcpu);
params[3] = (u32)kvm_rsi_read(vcpu);
params[4] = (u32)kvm_rdi_read(vcpu);
params[5] = (u32)kvm_rbp_read(vcpu);
}
#ifdef CONFIG_X86_64
else {
params[0] = (u64)kvm_rdi_read(vcpu);
params[1] = (u64)kvm_rsi_read(vcpu);
params[2] = (u64)kvm_rdx_read(vcpu);
params[3] = (u64)kvm_r10_read(vcpu);
params[4] = (u64)kvm_r8_read(vcpu);
params[5] = (u64)kvm_r9_read(vcpu);
}
#endif
trace_kvm_xen_hypercall(input, params[0], params[1], params[2],
params[3], params[4], params[5]);
vcpu->run->exit_reason = KVM_EXIT_XEN;
vcpu->run->xen.type = KVM_EXIT_XEN_HCALL;
vcpu->run->xen.u.hcall.longmode = longmode;
vcpu->run->xen.u.hcall.cpl = kvm_x86_ops.get_cpl(vcpu);
vcpu->run->xen.u.hcall.input = input;
vcpu->run->xen.u.hcall.params[0] = params[0];
vcpu->run->xen.u.hcall.params[1] = params[1];
vcpu->run->xen.u.hcall.params[2] = params[2];
vcpu->run->xen.u.hcall.params[3] = params[3];
vcpu->run->xen.u.hcall.params[4] = params[4];
vcpu->run->xen.u.hcall.params[5] = params[5];
vcpu->arch.xen.hypercall_rip = kvm_get_linear_rip(vcpu);
vcpu->arch.complete_userspace_io =
kvm_xen_hypercall_complete_userspace;
return 0;
}
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