Implement the VMLAUNCH and VMRESUME instructions, allowing a guest
hypervisor to run its own guests.
Signed-off-by: Nadav Har'El <nyh@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 205 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 202 insertions(+), 3 deletions(-)
--- .before/arch/x86/kvm/vmx.c 2011-01-26 18:06:05.000000000 +0200
+++ .after/arch/x86/kvm/vmx.c 2011-01-26 18:06:05.000000000 +0200
@@ -341,6 +341,10 @@ struct nested_vmx {
/* list of real (hardware) VMCS, one for each L2 guest of L1 */
struct list_head vmcs02_list; /* a vmcs_list */
int vmcs02_num;
+
+ /* Saving the VMCS that we used for running L1 */
+ struct saved_vmcs saved_vmcs01;
+ struct vmcs_fields *vmcs01_fields;
};
struct vcpu_vmx {
@@ -4453,6 +4457,10 @@ static int handle_vmon(struct kvm_vcpu *
INIT_LIST_HEAD(&(vmx->nested.vmcs02_list));
vmx->nested.vmcs02_num = 0;
+ vmx->nested.vmcs01_fields = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!vmx->nested.vmcs01_fields)
+ return -ENOMEM;
+
vmx->nested.vmxon = true;
skip_emulated_instruction(vcpu);
@@ -4505,6 +4513,9 @@ static void free_nested(struct vcpu_vmx
}
nested_free_all_vmcs(vmx);
+
+ kfree(vmx->nested.vmcs01_fields);
+ vmx->nested.vmcs01_fields = NULL;
}
/* Emulate the VMXOFF instruction */
@@ -4665,6 +4676,60 @@ static int handle_vmclear(struct kvm_vcp
return 1;
}
+static int nested_vmx_run(struct kvm_vcpu *vcpu);
+
+static int handle_launch_or_resume(struct kvm_vcpu *vcpu, bool launch)
+{
+ struct vmcs12 *vmcs12;
+ if (!nested_vmx_check_permission(vcpu))
+ return 1;
+
+ skip_emulated_instruction(vcpu);
+
+ vmcs12 = get_vmcs12(vcpu);
+ /* yet another strange pre-requisite listed in the VMX spec */
+ if (vmcs12->fields.guest_interruptibility_info &
+ GUEST_INTR_STATE_MOV_SS) {
+ nested_vmx_failValid(vcpu,
+ VMXERR_ENTRY_EVENTS_BLOCKED_BY_MOV_SS);
+ return 1;
+ }
+ /*
+ * enforce that after VMCLEAR, L1 must use VMLAUNCH, but later must use
+ * VMRESUME, as this is part of the spec (even though it was easier for
+ * us to just allow both to work any time).
+ */
+ if (vmcs12->launch_state == launch) {
+ nested_vmx_failValid(vcpu,
+ launch ? VMXERR_VMLAUNCH_NONCLEAR_VMCS :
+ VMXERR_VMRESUME_NONLAUNCHED_VMCS);
+ return 1;
+ }
+
+ nested_vmx_run(vcpu);
+
+ /*
+ * Note no nested_vmx_succeed or nested_vmx_fail here. At this point
+ * we are no longer running L1, and VMLAUNCH/VMRESUME has not yet
+ * returned as far as L1 is concerned. It will only return (and set
+ * the success flag) when L2 exits (see nested_vmx_vmexit()).
+ */
+ return 1;
+}
+
+/* Emulate the VMLAUNCH instruction */
+static int handle_vmlaunch(struct kvm_vcpu *vcpu)
+{
+ return handle_launch_or_resume(vcpu, true);
+}
+
+/* Emulate the VMRESUME instruction */
+static int handle_vmresume(struct kvm_vcpu *vcpu)
+{
+
+ return handle_launch_or_resume(vcpu, false);
+}
+
enum vmcs_field_type {
VMCS_FIELD_TYPE_U16 = 0,
VMCS_FIELD_TYPE_U64 = 1,
@@ -4941,11 +5006,11 @@ static int (*kvm_vmx_exit_handlers[])(st
[EXIT_REASON_INVLPG] = handle_invlpg,
[EXIT_REASON_VMCALL] = handle_vmcall,
[EXIT_REASON_VMCLEAR] = handle_vmclear,
- [EXIT_REASON_VMLAUNCH] = handle_vmx_insn,
+ [EXIT_REASON_VMLAUNCH] = handle_vmlaunch,
[EXIT_REASON_VMPTRLD] = handle_vmptrld,
[EXIT_REASON_VMPTRST] = handle_vmptrst,
[EXIT_REASON_VMREAD] = handle_vmread,
- [EXIT_REASON_VMRESUME] = handle_vmx_insn,
+ [EXIT_REASON_VMRESUME] = handle_vmresume,
[EXIT_REASON_VMWRITE] = handle_vmwrite,
[EXIT_REASON_VMOFF] = handle_vmoff,
[EXIT_REASON_VMON] = handle_vmon,
@@ -5009,7 +5074,8 @@ static int vmx_handle_exit(struct kvm_vc
"(0x%x) and exit reason is 0x%x\n",
__func__, vectoring_info, exit_reason);
- if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked)) {
+ if (!is_guest_mode(vcpu) &&
+ unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked)) {
if (vmx_interrupt_allowed(vcpu)) {
vmx->soft_vnmi_blocked = 0;
} else if (vmx->vnmi_blocked_time > 1000000000LL &&
@@ -5944,6 +6010,139 @@ int prepare_vmcs02(struct kvm_vcpu *vcpu
return 0;
}
+/*
+ * Return the cr0 value that a guest would read. This is a combination of
+ * the real cr0 used to run the guest (guest_cr0), and the bits shadowed by
+ * the hypervisor (cr0_read_shadow).
+ */
+static inline unsigned long guest_readable_cr0(struct vmcs_fields *fields)
+{
+ return (fields->guest_cr0 & ~fields->cr0_guest_host_mask) |
+ (fields->cr0_read_shadow & fields->cr0_guest_host_mask);
+}
+static inline unsigned long guest_readable_cr4(struct vmcs_fields *fields)
+{
+ return (fields->guest_cr4 & ~fields->cr4_guest_host_mask) |
+ (fields->cr4_read_shadow & fields->cr4_guest_host_mask);
+}
+static inline void set_cr3_and_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
+{
+ vcpu->arch.cr3 = cr3;
+ vmcs_writel(GUEST_CR3, cr3);
+ __set_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail);
+ load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3);
+ vmcs_write64(GUEST_PDPTR0, vcpu->arch.mmu.pdptrs[0]);
+ vmcs_write64(GUEST_PDPTR1, vcpu->arch.mmu.pdptrs[1]);
+ vmcs_write64(GUEST_PDPTR2, vcpu->arch.mmu.pdptrs[2]);
+ vmcs_write64(GUEST_PDPTR3, vcpu->arch.mmu.pdptrs[3]);
+}
+
+static int nested_vmx_run(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ int cpu;
+ struct saved_vmcs *saved_vmcs02;
+
+ enter_guest_mode(vcpu);
+ sync_cached_regs_to_vmcs(vcpu);
+ save_vmcs(vmx->nested.vmcs01_fields);
+
+ /*
+ * Switch from L1's VMCS, to L2's VMCS. Remember the L1 VMCS, on which
+ * CPU it was last loaded, and whether it was launched (we need all
+ * these values next time we will use L1). Then recall these values as
+ * they were for L2's VMCS (unless L2 has never been launched).
+ */
+ vmx->nested.saved_vmcs01.vmcs = vmx->vmcs;
+ vmx->nested.saved_vmcs01.cpu = vcpu->cpu;
+ vmx->nested.saved_vmcs01.launched = vmx->launched;
+
+ saved_vmcs02 = nested_get_current_vmcs(vmx);
+ if (!saved_vmcs02) {
+ /* In the current code, this cannot happen */
+ kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+ return 1;
+ }
+ vmx->vmcs = saved_vmcs02->vmcs;
+ vcpu->cpu = saved_vmcs02->cpu;
+ vmx->launched = saved_vmcs02->launched;
+
+ vmx_vcpu_put(vcpu);
+ cpu = get_cpu();
+ vmx_vcpu_load(vcpu, cpu);
+ vcpu->cpu = cpu;
+ put_cpu();
+
+ vmx->nested.current_vmcs12->launch_state = 1;
+
+ prepare_vmcs02(vcpu,
+ get_vmcs12_fields(vcpu), vmx->nested.vmcs01_fields);
+
+ if (get_vmcs12_fields(vcpu)->vm_entry_controls &
+ VM_ENTRY_IA32E_MODE)
+ vcpu->arch.efer |= (EFER_LMA | EFER_LME);
+ else
+ vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
+
+ vmx->rmode.vm86_active =
+ !(get_vmcs12_fields(vcpu)->cr0_read_shadow & X86_CR0_PE);
+
+ /* vmx_set_cr0() sets the cr0 that L2 will read, to be the one that L1
+ * dictated, and takes appropriate actions for special cr0 bits (like
+ * real mode, etc.).
+ */
+ vmx_set_cr0(vcpu, guest_readable_cr0(get_vmcs12_fields(vcpu)));
+
+ /* However, vmx_set_cr0 incorrectly enforces KVM's relationship between
+ * GUEST_CR0 and CR0_READ_SHADOW, e.g., that the former is the same as
+ * the latter with with TS added if !fpu_active. We need to take the
+ * actual GUEST_CR0 that L1 wanted, just with added TS if !fpu_active
+ * like KVM wants (for the "lazy fpu" feature, to avoid the costly
+ * restoration of fpu registers until the FPU is really used).
+ */
+ vmcs_writel(GUEST_CR0, get_vmcs12_fields(vcpu)->guest_cr0 |
+ (vcpu->fpu_active ? 0 : X86_CR0_TS));
+
+ /* we have to set the X86_CR0_PG bit of the cached cr0, because
+ * kvm_mmu_reset_context enables paging only if X86_CR0_PG is set in
+ * CR0 (we need the paging so that KVM treat this guest as a paging
+ * guest so we can easly forward page faults to L1.)
+ */
+ vcpu->arch.cr0 |= X86_CR0_PG;
+
+ if (enable_ept) {
+ /* shadow page tables on EPT */
+ vcpu->arch.cr4 = guest_readable_cr4(get_vmcs12_fields(vcpu));
+ vmcs_writel(CR4_READ_SHADOW, vcpu->arch.cr4);
+ vmcs_writel(GUEST_CR4, get_vmcs12_fields(vcpu)->guest_cr4);
+ set_cr3_and_pdptrs(vcpu, get_vmcs12_fields(vcpu)->guest_cr3);
+ } else {
+ /* shadow page tables on shadow page tables */
+ vmx_set_cr4(vcpu, get_vmcs12_fields(vcpu)->guest_cr4);
+ vmcs_writel(CR4_READ_SHADOW,
+ get_vmcs12_fields(vcpu)->cr4_read_shadow);
+ kvm_set_cr3(vcpu, get_vmcs12_fields(vcpu)->guest_cr3);
+ kvm_mmu_reset_context(vcpu);
+
+ if (unlikely(kvm_mmu_load(vcpu))) {
+ /*
+ * TODO: there is no reasonable error number to use.
+ * perhaps a more reasonable thing to do is to
+ * emulate a guest shutdown, not a launch error?
+ */
+ nested_vmx_failValid(vcpu, 87);
+ return 1;
+ }
+ }
+
+ kvm_register_write(vcpu, VCPU_REGS_RSP,
+ get_vmcs12_fields(vcpu)->guest_rsp);
+ kvm_register_write(vcpu, VCPU_REGS_RIP,
+ get_vmcs12_fields(vcpu)->guest_rip);
+
+ return 1;
+}
+
static struct kvm_x86_ops vmx_x86_ops = {
.cpu_has_kvm_support = cpu_has_kvm_support,
.disabled_by_bios = vmx_disabled_by_bios,
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