This patch implements nested_vmx_vmexit(), called when the nested L2 guest
exits and we want to run its L1 parent and let it handle this exit.
Note that this will not necessarily be called on every L2 exit. L0 may decide
to handle a particular exit on its own, without L1's involvement; In that
case, L0 will handle the exit, and resume running L2, without running L1 and
without calling nested_vmx_vmexit(). The logic for deciding whether to handle
a particular exit in L1 or in L0, i.e., whether to call nested_vmx_vmexit(),
will appear in the next patch.
Signed-off-by: Nadav Har'El <n...@il.ibm.com>
---
arch/x86/kvm/vmx.c | 248 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 248 insertions(+)
--- .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
@@ -5217,6 +5217,8 @@ static void __vmx_complete_interrupts(st
static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
{
+ if (is_guest_mode(&vmx->vcpu))
+ return;
__vmx_complete_interrupts(vmx, vmx->idt_vectoring_info,
VM_EXIT_INSTRUCTION_LEN,
IDT_VECTORING_ERROR_CODE);
@@ -6137,6 +6139,252 @@ static int nested_vmx_run(struct kvm_vcp
return 1;
}
+/*
+ * On a nested exit from L2 to L1, vmcs12.guest_cr0 might not be up-to-date
+ * because L2 may have changed some cr0 bits directly (see CRO_GUEST_HOST_MASK)
+ * without L0 trapping the change and updating vmcs12.
+ * This function returns the value we should put in vmcs12.guest_cr0. It's not
+ * enough to just return the current (vmcs02) GUEST_CR0. This may not be the
+ * guest cr0 that L1 thought it was giving its L2 guest - it is possible that
+ * L1 wished to allow its guest to set a cr0 bit directly, but we (L0) asked
+ * to trap this change and instead set just the read shadow. If this is the
+ * case, we need to copy these read-shadow bits back to vmcs12.guest_cr0, where
+ * L1 believes they already are.
+ */
+static inline unsigned long
+vmcs12_guest_cr0(struct kvm_vcpu *vcpu, struct vmcs_fields *vmcs12)
+{
+ unsigned long guest_cr0_bits =
+ vcpu->arch.cr0_guest_owned_bits | vmcs12->cr0_guest_host_mask;
+ return (vmcs_readl(GUEST_CR0) & guest_cr0_bits) |
+ (vmcs_readl(CR0_READ_SHADOW) & ~guest_cr0_bits);
+}
+
+static inline unsigned long
+vmcs12_guest_cr4(struct kvm_vcpu *vcpu, struct vmcs_fields *vmcs12)
+{
+ unsigned long guest_cr4_bits =
+ vcpu->arch.cr4_guest_owned_bits | vmcs12->cr4_guest_host_mask;
+ return (vmcs_readl(GUEST_CR4) & guest_cr4_bits) |
+ (vmcs_readl(CR4_READ_SHADOW) & ~guest_cr4_bits);
+}
+
+/*
+ * prepare_vmcs12 is called when the nested L2 guest exits and we want to
+ * prepare to run its L1 parent. L1 keeps a vmcs for L2 (vmcs12), and this
+ * function updates it to reflect the changes to the guest state while L2 was
+ * running (and perhaps made some exits which were handled directly by L0
+ * without going back to L1), and to reflect the exit reason.
+ * Note that we do not have to copy here all VMCS fields, just those that
+ * could have changed by the L2 guest or the exit - i.e., the guest-state and
+ * exit-information fields only. Other fields are modified by L1 with VMWRITE,
+ * which already writes to vmcs12 directly.
+ */
+void prepare_vmcs12(struct kvm_vcpu *vcpu)
+{
+ struct vmcs_fields *vmcs12 = get_vmcs12_fields(vcpu);
+
+ /* update guest state fields: */
+ vmcs12->guest_cr0 = vmcs12_guest_cr0(vcpu, vmcs12);
+ vmcs12->guest_cr4 = vmcs12_guest_cr4(vcpu, vmcs12);
+
+ vmcs12->guest_dr7 = vmcs_readl(GUEST_DR7);
+ vmcs12->guest_rsp = vmcs_readl(GUEST_RSP);
+ vmcs12->guest_rip = vmcs_readl(GUEST_RIP);
+ vmcs12->guest_rflags = vmcs_readl(GUEST_RFLAGS);
+
+ vmcs12->guest_es_selector = vmcs_read16(GUEST_ES_SELECTOR);
+ vmcs12->guest_cs_selector = vmcs_read16(GUEST_CS_SELECTOR);
+ vmcs12->guest_ss_selector = vmcs_read16(GUEST_SS_SELECTOR);
+ vmcs12->guest_ds_selector = vmcs_read16(GUEST_DS_SELECTOR);
+ vmcs12->guest_fs_selector = vmcs_read16(GUEST_FS_SELECTOR);
+ vmcs12->guest_gs_selector = vmcs_read16(GUEST_GS_SELECTOR);
+ vmcs12->guest_ldtr_selector = vmcs_read16(GUEST_LDTR_SELECTOR);
+ vmcs12->guest_tr_selector = vmcs_read16(GUEST_TR_SELECTOR);
+ vmcs12->guest_es_limit = vmcs_read32(GUEST_ES_LIMIT);
+ vmcs12->guest_cs_limit = vmcs_read32(GUEST_CS_LIMIT);
+ vmcs12->guest_ss_limit = vmcs_read32(GUEST_SS_LIMIT);
+ vmcs12->guest_ds_limit = vmcs_read32(GUEST_DS_LIMIT);
+ vmcs12->guest_fs_limit = vmcs_read32(GUEST_FS_LIMIT);
+ vmcs12->guest_gs_limit = vmcs_read32(GUEST_GS_LIMIT);
+ vmcs12->guest_ldtr_limit = vmcs_read32(GUEST_LDTR_LIMIT);
+ vmcs12->guest_tr_limit = vmcs_read32(GUEST_TR_LIMIT);
+ vmcs12->guest_gdtr_limit = vmcs_read32(GUEST_GDTR_LIMIT);
+ vmcs12->guest_idtr_limit = vmcs_read32(GUEST_IDTR_LIMIT);
+ vmcs12->guest_es_ar_bytes = vmcs_read32(GUEST_ES_AR_BYTES);
+ vmcs12->guest_cs_ar_bytes = vmcs_read32(GUEST_CS_AR_BYTES);
+ vmcs12->guest_ss_ar_bytes = vmcs_read32(GUEST_SS_AR_BYTES);
+ vmcs12->guest_ds_ar_bytes = vmcs_read32(GUEST_DS_AR_BYTES);
+ vmcs12->guest_fs_ar_bytes = vmcs_read32(GUEST_FS_AR_BYTES);
+ vmcs12->guest_gs_ar_bytes = vmcs_read32(GUEST_GS_AR_BYTES);
+ vmcs12->guest_ldtr_ar_bytes = vmcs_read32(GUEST_LDTR_AR_BYTES);
+ vmcs12->guest_tr_ar_bytes = vmcs_read32(GUEST_TR_AR_BYTES);
+ vmcs12->guest_es_base = vmcs_readl(GUEST_ES_BASE);
+ vmcs12->guest_cs_base = vmcs_readl(GUEST_CS_BASE);
+ vmcs12->guest_ss_base = vmcs_readl(GUEST_SS_BASE);
+ vmcs12->guest_ds_base = vmcs_readl(GUEST_DS_BASE);
+ vmcs12->guest_fs_base = vmcs_readl(GUEST_FS_BASE);
+ vmcs12->guest_gs_base = vmcs_readl(GUEST_GS_BASE);
+ vmcs12->guest_ldtr_base = vmcs_readl(GUEST_LDTR_BASE);
+ vmcs12->guest_tr_base = vmcs_readl(GUEST_TR_BASE);
+ vmcs12->guest_gdtr_base = vmcs_readl(GUEST_GDTR_BASE);
+ vmcs12->guest_idtr_base = vmcs_readl(GUEST_IDTR_BASE);
+
+ vmcs12->guest_activity_state = vmcs_read32(GUEST_ACTIVITY_STATE);
+ vmcs12->guest_interruptibility_info =
+ vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
+ vmcs12->guest_pending_dbg_exceptions =
+ vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
+ vmcs12->vmcs_link_pointer = vmcs_read64(VMCS_LINK_POINTER);
+
+ /* TODO: These cannot have changed unless we have MSR bitmaps and
+ * the relevant bit asks not to trap the change */
+ vmcs12->guest_ia32_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL);
+ if (vmcs_config.vmentry_ctrl & VM_EXIT_SAVE_IA32_PAT)
+ vmcs12->guest_ia32_pat = vmcs_read64(GUEST_IA32_PAT);
+ vmcs12->guest_sysenter_cs = vmcs_read32(GUEST_SYSENTER_CS);
+ vmcs12->guest_sysenter_esp = vmcs_readl(GUEST_SYSENTER_ESP);
+ vmcs12->guest_sysenter_eip = vmcs_readl(GUEST_SYSENTER_EIP);
+
+ /* update exit information fields: */
+
+ vmcs12->vm_exit_reason = vmcs_read32(VM_EXIT_REASON);
+ vmcs12->exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
+
+ vmcs12->vm_exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
+ vmcs12->vm_exit_intr_error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
+ vmcs12->idt_vectoring_info_field =
+ vmcs_read32(IDT_VECTORING_INFO_FIELD);
+ vmcs12->idt_vectoring_error_code =
+ vmcs_read32(IDT_VECTORING_ERROR_CODE);
+ vmcs12->vm_exit_instruction_len = vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+ vmcs12->vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+
+ /* clear vm-entry fields which are to be cleared on exit */
+ if (!(vmcs12->vm_exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
+ vmcs12->vm_entry_intr_info_field &= ~INTR_INFO_VALID_MASK;
+}
+
+/*
+ * Emulate an exit from nested guest (L2) to L1, i.e., prepare to run L1
+ * and modify vmcs12 to make it see what it would expect to see there if
+ * L2 was its real guest. Must only be called when in L2 (is_guest_mode())
+ */
+static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, bool is_interrupt)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs_fields *vmcs01 = vmx->nested.vmcs01_fields;
+ int cpu;
+ struct saved_vmcs *saved_vmcs02;
+
+ leave_guest_mode(vcpu);
+
+ sync_cached_regs_to_vmcs(vcpu);
+
+ prepare_vmcs12(vcpu);
+
+ if (is_interrupt)
+ get_vmcs12_fields(vcpu)->vm_exit_reason =
+ EXIT_REASON_EXTERNAL_INTERRUPT;
+
+ /*
+ * Switch from L2's VMCS, to L1's VMCS. Remember on which CPU the L2
+ * VMCS was last loaded, and whether it was launched (we need to know
+ * this next time we use L2), and recall these values as they were for
+ * L1's VMCS.
+ */
+ saved_vmcs02 = nested_get_current_vmcs(vmx);
+ if (saved_vmcs02) {
+ saved_vmcs02->cpu = vcpu->cpu;
+ saved_vmcs02->launched = vmx->launched;
+ }
+ vmx->vmcs = vmx->nested.saved_vmcs01.vmcs;
+ vcpu->cpu = vmx->nested.saved_vmcs01.cpu;
+ vmx->launched = vmx->nested.saved_vmcs01.launched;
+
+ vmx_vcpu_put(vcpu);
+ cpu = get_cpu();
+ vmx_vcpu_load(vcpu, cpu);
+ vcpu->cpu = cpu;
+ put_cpu();
+
+ if (get_vmcs12_fields(vcpu)->vm_exit_controls &
+ VM_EXIT_HOST_ADDR_SPACE_SIZE)
+ vcpu->arch.efer |= (EFER_LMA | EFER_LME);
+ else
+ vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
+ vmx_set_efer(vcpu, vcpu->arch.efer);
+
+ /*
+ * L2 perhaps switched to real mode and set vmx->rmode, but we're back
+ * in L1 and as it is running VMX, it can't be in real mode.
+ */
+ vmx->rmode.vm86_active = 0;
+
+ /*
+ * If L1 set the HOST_* fields in the VMCS, when exiting from L2 to L1
+ * we need to return those, not L1's old values.
+ */
+ vmcs_writel(GUEST_RIP, get_vmcs12_fields(vcpu)->host_rip);
+ vmcs_writel(GUEST_RSP, get_vmcs12_fields(vcpu)->host_rsp);
+ vmcs01->cr0_read_shadow = get_vmcs12_fields(vcpu)->host_cr0;
+
+ /*
+ * We're running a regular L1 guest again, so we do the regular KVM
+ * thing: run vmx_set_cr0 with the cr0 bits the guest thinks it has.
+ * vmx_set_cr0 might use slightly different bits on the new guest_cr0
+ * it sets, e.g., add TS when !fpu_active.
+ * Note that vmx_set_cr0 refers to rmode and efer set above.
+ */
+ vmx_set_cr0(vcpu, guest_readable_cr0(vmcs01));
+ /*
+ * If we did fpu_activate()/fpu_deactive() during l2's run, we need to
+ * apply the same changes to l1's vmcs. We just set cr0 correctly, but
+ * now we need to also update cr0_guest_host_mask and exception_bitmap.
+ */
+ vmcs_write32(EXCEPTION_BITMAP,
+ (vmcs01->exception_bitmap & ~(1u<<NM_VECTOR)) |
+ (vcpu->fpu_active ? 0 : (1u<<NM_VECTOR)));
+ vcpu->arch.cr0_guest_owned_bits = (vcpu->fpu_active ? X86_CR0_TS : 0);
+ vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
+
+ vmx_set_cr4(vcpu, guest_readable_cr4(vmcs01));
+ vcpu->arch.cr4_guest_owned_bits = ~vmcs01->cr4_guest_host_mask;
+
+ if (enable_ept) {
+ /* shadow page tables on EPT: */
+ set_cr3_and_pdptrs(vcpu, get_vmcs12_fields(vcpu)->host_cr3);
+ } else {
+ /* shadow page tables on shadow page tables: */
+ kvm_set_cr3(vcpu, get_vmcs12_fields(vcpu)->host_cr3);
+ kvm_mmu_reset_context(vcpu);
+ kvm_mmu_load(vcpu);
+ }
+ if (enable_vpid) {
+ /*
+ * Trivially support vpid by letting L2s share their parent
+ * L1's vpid. TODO: move to a more elaborate solution, giving
+ * each L2 its own vpid and exposing the vpid feature to L1.
+ */
+ vmx_flush_tlb(vcpu);
+ }
+
+ kvm_register_write(vcpu, VCPU_REGS_RSP, vmcs01->guest_rsp);
+ kvm_register_write(vcpu, VCPU_REGS_RIP, vmcs01->guest_rip);
+
+ if (unlikely(vmx->fail)) {
+ /*
+ * When L1 launches L2 and then we (L0) fail to launch L2,
+ * we nested_vmx_vmexit back to L1, but now should let it know
+ * that the VMLAUNCH failed - with the same error that we
+ * got when launching L2.
+ */
+ vmx->fail = 0;
+ nested_vmx_failValid(vcpu, vmcs_read32(VM_INSTRUCTION_ERROR));
+ } else
+ nested_vmx_succeed(vcpu);
+}
+
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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