1 files changed, 431 insertions, 0 deletions

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
new file mode 100644
index 000000000000..af8f6562fce4
--- /dev/null
+++ b/arch/x86/kvm/xen.c
@@ -0,0 +1,431 @@
+// 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)
+{
+	gpa_t gpa = gfn_to_gpa(gfn);
+	int wc_ofs, sec_hi_ofs;
+	int ret;
+	int idx = srcu_read_lock(&kvm->srcu);
+
+	ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
+					gpa, PAGE_SIZE);
+	if (ret)
+		goto out;
+
+	kvm->arch.xen.shinfo_set = true;
+
+	/* Paranoia checks on the 32-bit struct layout */
+	BUILD_BUG_ON(offsetof(struct compat_shared_info, wc) != 0x900);
+	BUILD_BUG_ON(offsetof(struct compat_shared_info, arch.wc_sec_hi) != 0x924);
+	BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0);
+
+	/* 32-bit location by default */
+	wc_ofs = offsetof(struct compat_shared_info, wc);
+	sec_hi_ofs = offsetof(struct compat_shared_info, arch.wc_sec_hi);
+
+#ifdef CONFIG_X86_64
+	/* Paranoia checks on the 64-bit struct layout */
+	BUILD_BUG_ON(offsetof(struct shared_info, wc) != 0xc00);
+	BUILD_BUG_ON(offsetof(struct shared_info, wc_sec_hi) != 0xc0c);
+
+	if (kvm->arch.xen.long_mode) {
+		wc_ofs = offsetof(struct shared_info, wc);
+		sec_hi_ofs = offsetof(struct shared_info, wc_sec_hi);
+	}
+#endif
+
+	kvm_write_wall_clock(kvm, gpa + wc_ofs, sec_hi_ofs - wc_ofs);
+	kvm_make_all_cpus_request(kvm, KVM_REQ_MASTERCLOCK_UPDATE);
+
+out:
+	srcu_read_unlock(&kvm->srcu, idx);
+	return ret;
+}
+
+int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
+{
+	u8 rc = 0;
+
+	/*
+	 * If the global upcall vector (HVMIRQ_callback_vector) is set and
+	 * the vCPU's evtchn_upcall_pending flag is set, the IRQ is pending.
+	 */
+	struct gfn_to_hva_cache *ghc = &v->arch.xen.vcpu_info_cache;
+	struct kvm_memslots *slots = kvm_memslots(v->kvm);
+	unsigned int offset = offsetof(struct vcpu_info, evtchn_upcall_pending);
+
+	/* No need for compat handling here */
+	BUILD_BUG_ON(offsetof(struct vcpu_info, evtchn_upcall_pending) !=
+		     offsetof(struct compat_vcpu_info, evtchn_upcall_pending));
+	BUILD_BUG_ON(sizeof(rc) !=
+		     sizeof(((struct vcpu_info *)0)->evtchn_upcall_pending));
+	BUILD_BUG_ON(sizeof(rc) !=
+		     sizeof(((struct compat_vcpu_info *)0)->evtchn_upcall_pending));
+
+	/*
+	 * For efficiency, this mirrors the checks for using the valid
+	 * cache in kvm_read_guest_offset_cached(), but just uses
+	 * __get_user() instead. And falls back to the slow path.
+	 */
+	if (likely(slots->generation == ghc->generation &&
+		   !kvm_is_error_hva(ghc->hva) && ghc->memslot)) {
+		/* Fast path */
+		__get_user(rc, (u8 __user *)ghc->hva + offset);
+	} else {
+		/* Slow path */
+		kvm_read_guest_offset_cached(v->kvm, ghc, &rc, offset,
+					     sizeof(rc));
+	}
+
+	return rc;
+}
+
+int kvm_xen_hvm_set_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:
+		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:
+		if (data->u.shared_info.gfn == GPA_INVALID) {
+			kvm->arch.xen.shinfo_set = false;
+			r = 0;
+			break;
+		}
+		r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
+		break;
+
+
+	case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
+		if (data->u.vector && data->u.vector < 0x10)
+			r = -EINVAL;
+		else {
+			kvm->arch.xen.upcall_vector = data->u.vector;
+			r = 0;
+		}
+		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);
+		else
+			data->u.shared_info.gfn = GPA_INVALID;
+		r = 0;
+		break;
+
+	case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
+		data->u.vector = kvm->arch.xen.upcall_vector;
+		r = 0;
+		break;
+
+	default:
+		break;
+	}
+
+	mutex_unlock(&kvm->lock);
+	return r;
+}
+
+int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
+{
+	int idx, r = -ENOENT;
+
+	mutex_lock(&vcpu->kvm->lock);
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+	switch (data->type) {
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO:
+		/* No compat necessary here. */
+		BUILD_BUG_ON(sizeof(struct vcpu_info) !=
+			     sizeof(struct compat_vcpu_info));
+
+		if (data->u.gpa == GPA_INVALID) {
+			vcpu->arch.xen.vcpu_info_set = false;
+			break;
+		}
+
+		r = kvm_gfn_to_hva_cache_init(vcpu->kvm,
+					      &vcpu->arch.xen.vcpu_info_cache,
+					      data->u.gpa,
+					      sizeof(struct vcpu_info));
+		if (!r) {
+			vcpu->arch.xen.vcpu_info_set = true;
+			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+		}
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
+		if (data->u.gpa == GPA_INVALID) {
+			vcpu->arch.xen.vcpu_time_info_set = false;
+			break;
+		}
+
+		r = kvm_gfn_to_hva_cache_init(vcpu->kvm,
+					      &vcpu->arch.xen.vcpu_time_info_cache,
+					      data->u.gpa,
+					      sizeof(struct pvclock_vcpu_time_info));
+		if (!r) {
+			vcpu->arch.xen.vcpu_time_info_set = true;
+			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+		}
+		break;
+
+	default:
+		break;
+	}
+
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+	mutex_unlock(&vcpu->kvm->lock);
+	return r;
+}
+
+int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
+{
+	int r = -ENOENT;
+
+	mutex_lock(&vcpu->kvm->lock);
+
+	switch (data->type) {
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO:
+		if (vcpu->arch.xen.vcpu_info_set)
+			data->u.gpa = vcpu->arch.xen.vcpu_info_cache.gpa;
+		else
+			data->u.gpa = GPA_INVALID;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
+		if (vcpu->arch.xen.vcpu_time_info_set)
+			data->u.gpa = vcpu->arch.xen.vcpu_time_info_cache.gpa;
+		else
+			data->u.gpa = GPA_INVALID;
+		r = 0;
+		break;
+
+	default:
+		break;
+	}
+
+	mutex_unlock(&vcpu->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 {
+		/*
+		 * Note, truncation is a non-issue as 'lm' is guaranteed to be
+		 * false for a 32-bit kernel, i.e. when hva_t is only 4 bytes.
+		 */
+		hva_t 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))
+		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;
+}