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KVM: nVMX: Prepare vmcs02 from vmcs01 and vmcs12
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This patch contains code to prepare the VMCS which can be used to actually
run the L2 guest, vmcs02. prepare_vmcs02 appropriately merges the information
in vmcs12 (the vmcs that L1 built for L2) and in vmcs01 (our desires for our
own guests).

Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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Nadav Har'El authored and Avi Kivity committed Jul 12, 2011
1 parent bf8179a commit fe3ef05
Showing 1 changed file with 279 additions and 0 deletions.
279 changes: 279 additions & 0 deletions arch/x86/kvm/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -345,6 +345,12 @@ struct nested_vmx {
/* vmcs02_list cache of VMCSs recently used to run L2 guests */
struct list_head vmcs02_pool;
int vmcs02_num;
u64 vmcs01_tsc_offset;
/*
* Guest pages referred to in vmcs02 with host-physical pointers, so
* we must keep them pinned while L2 runs.
*/
struct page *apic_access_page;
};

struct vcpu_vmx {
Expand Down Expand Up @@ -847,6 +853,18 @@ static inline bool report_flexpriority(void)
return flexpriority_enabled;
}

static inline bool nested_cpu_has(struct vmcs12 *vmcs12, u32 bit)
{
return vmcs12->cpu_based_vm_exec_control & bit;
}

static inline bool nested_cpu_has2(struct vmcs12 *vmcs12, u32 bit)
{
return (vmcs12->cpu_based_vm_exec_control &
CPU_BASED_ACTIVATE_SECONDARY_CONTROLS) &&
(vmcs12->secondary_vm_exec_control & bit);
}

static int __find_msr_index(struct vcpu_vmx *vmx, u32 msr)
{
int i;
Expand Down Expand Up @@ -1441,6 +1459,22 @@ static void vmx_fpu_activate(struct kvm_vcpu *vcpu)

static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu);

/*
* Return the cr0 value that a nested guest would read. This is a combination
* of the real cr0 used to run the guest (guest_cr0), and the bits shadowed by
* its hypervisor (cr0_read_shadow).
*/
static inline unsigned long nested_read_cr0(struct vmcs12 *fields)
{
return (fields->guest_cr0 & ~fields->cr0_guest_host_mask) |
(fields->cr0_read_shadow & fields->cr0_guest_host_mask);
}
static inline unsigned long nested_read_cr4(struct vmcs12 *fields)
{
return (fields->guest_cr4 & ~fields->cr4_guest_host_mask) |
(fields->cr4_read_shadow & fields->cr4_guest_host_mask);
}

static void vmx_fpu_deactivate(struct kvm_vcpu *vcpu)
{
vmx_decache_cr0_guest_bits(vcpu);
Expand Down Expand Up @@ -3438,6 +3472,9 @@ static void set_cr4_guest_host_mask(struct vcpu_vmx *vmx)
vmx->vcpu.arch.cr4_guest_owned_bits = KVM_CR4_GUEST_OWNED_BITS;
if (enable_ept)
vmx->vcpu.arch.cr4_guest_owned_bits |= X86_CR4_PGE;
if (is_guest_mode(&vmx->vcpu))
vmx->vcpu.arch.cr4_guest_owned_bits &=
~get_vmcs12(&vmx->vcpu)->cr4_guest_host_mask;
vmcs_writel(CR4_GUEST_HOST_MASK, ~vmx->vcpu.arch.cr4_guest_owned_bits);
}

Expand Down Expand Up @@ -4736,6 +4773,11 @@ static void free_nested(struct vcpu_vmx *vmx)
vmx->nested.current_vmptr = -1ull;
vmx->nested.current_vmcs12 = NULL;
}
/* Unpin physical memory we referred to in current vmcs02 */
if (vmx->nested.apic_access_page) {
nested_release_page(vmx->nested.apic_access_page);
vmx->nested.apic_access_page = 0;
}

nested_free_all_saved_vmcss(vmx);
}
Expand Down Expand Up @@ -5810,6 +5852,243 @@ static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
{
}

/*
* prepare_vmcs02 is called when the L1 guest hypervisor runs its nested
* L2 guest. L1 has a vmcs for L2 (vmcs12), and this function "merges" it
* with L0's requirements for its guest (a.k.a. vmsc01), so we can run the L2
* guest in a way that will both be appropriate to L1's requests, and our
* needs. In addition to modifying the active vmcs (which is vmcs02), this
* function also has additional necessary side-effects, like setting various
* vcpu->arch fields.
*/
static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 exec_control;

vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector);
vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector);
vmcs_write16(GUEST_SS_SELECTOR, vmcs12->guest_ss_selector);
vmcs_write16(GUEST_DS_SELECTOR, vmcs12->guest_ds_selector);
vmcs_write16(GUEST_FS_SELECTOR, vmcs12->guest_fs_selector);
vmcs_write16(GUEST_GS_SELECTOR, vmcs12->guest_gs_selector);
vmcs_write16(GUEST_LDTR_SELECTOR, vmcs12->guest_ldtr_selector);
vmcs_write16(GUEST_TR_SELECTOR, vmcs12->guest_tr_selector);
vmcs_write32(GUEST_ES_LIMIT, vmcs12->guest_es_limit);
vmcs_write32(GUEST_CS_LIMIT, vmcs12->guest_cs_limit);
vmcs_write32(GUEST_SS_LIMIT, vmcs12->guest_ss_limit);
vmcs_write32(GUEST_DS_LIMIT, vmcs12->guest_ds_limit);
vmcs_write32(GUEST_FS_LIMIT, vmcs12->guest_fs_limit);
vmcs_write32(GUEST_GS_LIMIT, vmcs12->guest_gs_limit);
vmcs_write32(GUEST_LDTR_LIMIT, vmcs12->guest_ldtr_limit);
vmcs_write32(GUEST_TR_LIMIT, vmcs12->guest_tr_limit);
vmcs_write32(GUEST_GDTR_LIMIT, vmcs12->guest_gdtr_limit);
vmcs_write32(GUEST_IDTR_LIMIT, vmcs12->guest_idtr_limit);
vmcs_write32(GUEST_ES_AR_BYTES, vmcs12->guest_es_ar_bytes);
vmcs_write32(GUEST_CS_AR_BYTES, vmcs12->guest_cs_ar_bytes);
vmcs_write32(GUEST_SS_AR_BYTES, vmcs12->guest_ss_ar_bytes);
vmcs_write32(GUEST_DS_AR_BYTES, vmcs12->guest_ds_ar_bytes);
vmcs_write32(GUEST_FS_AR_BYTES, vmcs12->guest_fs_ar_bytes);
vmcs_write32(GUEST_GS_AR_BYTES, vmcs12->guest_gs_ar_bytes);
vmcs_write32(GUEST_LDTR_AR_BYTES, vmcs12->guest_ldtr_ar_bytes);
vmcs_write32(GUEST_TR_AR_BYTES, vmcs12->guest_tr_ar_bytes);
vmcs_writel(GUEST_ES_BASE, vmcs12->guest_es_base);
vmcs_writel(GUEST_CS_BASE, vmcs12->guest_cs_base);
vmcs_writel(GUEST_SS_BASE, vmcs12->guest_ss_base);
vmcs_writel(GUEST_DS_BASE, vmcs12->guest_ds_base);
vmcs_writel(GUEST_FS_BASE, vmcs12->guest_fs_base);
vmcs_writel(GUEST_GS_BASE, vmcs12->guest_gs_base);
vmcs_writel(GUEST_LDTR_BASE, vmcs12->guest_ldtr_base);
vmcs_writel(GUEST_TR_BASE, vmcs12->guest_tr_base);
vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base);
vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base);

vmcs_write64(GUEST_IA32_DEBUGCTL, vmcs12->guest_ia32_debugctl);
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
vmcs12->vm_entry_intr_info_field);
vmcs_write32(VM_ENTRY_EXCEPTION_ERROR_CODE,
vmcs12->vm_entry_exception_error_code);
vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
vmcs12->vm_entry_instruction_len);
vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
vmcs12->guest_interruptibility_info);
vmcs_write32(GUEST_ACTIVITY_STATE, vmcs12->guest_activity_state);
vmcs_write32(GUEST_SYSENTER_CS, vmcs12->guest_sysenter_cs);
vmcs_writel(GUEST_DR7, vmcs12->guest_dr7);
vmcs_writel(GUEST_RFLAGS, vmcs12->guest_rflags);
vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS,
vmcs12->guest_pending_dbg_exceptions);
vmcs_writel(GUEST_SYSENTER_ESP, vmcs12->guest_sysenter_esp);
vmcs_writel(GUEST_SYSENTER_EIP, vmcs12->guest_sysenter_eip);

vmcs_write64(VMCS_LINK_POINTER, -1ull);

vmcs_write32(PIN_BASED_VM_EXEC_CONTROL,
(vmcs_config.pin_based_exec_ctrl |
vmcs12->pin_based_vm_exec_control));

/*
* Whether page-faults are trapped is determined by a combination of
* 3 settings: PFEC_MASK, PFEC_MATCH and EXCEPTION_BITMAP.PF.
* If enable_ept, L0 doesn't care about page faults and we should
* set all of these to L1's desires. However, if !enable_ept, L0 does
* care about (at least some) page faults, and because it is not easy
* (if at all possible?) to merge L0 and L1's desires, we simply ask
* to exit on each and every L2 page fault. This is done by setting
* MASK=MATCH=0 and (see below) EB.PF=1.
* Note that below we don't need special code to set EB.PF beyond the
* "or"ing of the EB of vmcs01 and vmcs12, because when enable_ept,
* vmcs01's EB.PF is 0 so the "or" will take vmcs12's value, and when
* !enable_ept, EB.PF is 1, so the "or" will always be 1.
*
* A problem with this approach (when !enable_ept) is that L1 may be
* injected with more page faults than it asked for. This could have
* caused problems, but in practice existing hypervisors don't care.
* To fix this, we will need to emulate the PFEC checking (on the L1
* page tables), using walk_addr(), when injecting PFs to L1.
*/
vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK,
enable_ept ? vmcs12->page_fault_error_code_mask : 0);
vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH,
enable_ept ? vmcs12->page_fault_error_code_match : 0);

if (cpu_has_secondary_exec_ctrls()) {
u32 exec_control = vmx_secondary_exec_control(vmx);
if (!vmx->rdtscp_enabled)
exec_control &= ~SECONDARY_EXEC_RDTSCP;
/* Take the following fields only from vmcs12 */
exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
if (nested_cpu_has(vmcs12,
CPU_BASED_ACTIVATE_SECONDARY_CONTROLS))
exec_control |= vmcs12->secondary_vm_exec_control;

if (exec_control & SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) {
/*
* Translate L1 physical address to host physical
* address for vmcs02. Keep the page pinned, so this
* physical address remains valid. We keep a reference
* to it so we can release it later.
*/
if (vmx->nested.apic_access_page) /* shouldn't happen */
nested_release_page(vmx->nested.apic_access_page);
vmx->nested.apic_access_page =
nested_get_page(vcpu, vmcs12->apic_access_addr);
/*
* If translation failed, no matter: This feature asks
* to exit when accessing the given address, and if it
* can never be accessed, this feature won't do
* anything anyway.
*/
if (!vmx->nested.apic_access_page)
exec_control &=
~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
else
vmcs_write64(APIC_ACCESS_ADDR,
page_to_phys(vmx->nested.apic_access_page));
}

vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
}


/*
* Set host-state according to L0's settings (vmcs12 is irrelevant here)
* Some constant fields are set here by vmx_set_constant_host_state().
* Other fields are different per CPU, and will be set later when
* vmx_vcpu_load() is called, and when vmx_save_host_state() is called.
*/
vmx_set_constant_host_state();

/*
* HOST_RSP is normally set correctly in vmx_vcpu_run() just before
* entry, but only if the current (host) sp changed from the value
* we wrote last (vmx->host_rsp). This cache is no longer relevant
* if we switch vmcs, and rather than hold a separate cache per vmcs,
* here we just force the write to happen on entry.
*/
vmx->host_rsp = 0;

exec_control = vmx_exec_control(vmx); /* L0's desires */
exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
exec_control &= ~CPU_BASED_VIRTUAL_NMI_PENDING;
exec_control &= ~CPU_BASED_TPR_SHADOW;
exec_control |= vmcs12->cpu_based_vm_exec_control;
/*
* Merging of IO and MSR bitmaps not currently supported.
* Rather, exit every time.
*/
exec_control &= ~CPU_BASED_USE_MSR_BITMAPS;
exec_control &= ~CPU_BASED_USE_IO_BITMAPS;
exec_control |= CPU_BASED_UNCOND_IO_EXITING;

vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, exec_control);

/* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the
* bitwise-or of what L1 wants to trap for L2, and what we want to
* trap. Note that CR0.TS also needs updating - we do this later.
*/
update_exception_bitmap(vcpu);
vcpu->arch.cr0_guest_owned_bits &= ~vmcs12->cr0_guest_host_mask;
vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);

/* Note: IA32_MODE, LOAD_IA32_EFER are modified by vmx_set_efer below */
vmcs_write32(VM_EXIT_CONTROLS,
vmcs12->vm_exit_controls | vmcs_config.vmexit_ctrl);
vmcs_write32(VM_ENTRY_CONTROLS, vmcs12->vm_entry_controls |
(vmcs_config.vmentry_ctrl & ~VM_ENTRY_IA32E_MODE));

if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT)
vmcs_write64(GUEST_IA32_PAT, vmcs12->guest_ia32_pat);
else if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT)
vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat);


set_cr4_guest_host_mask(vmx);

vmcs_write64(TSC_OFFSET,
vmx->nested.vmcs01_tsc_offset + vmcs12->tsc_offset);

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.
*/
vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
vmx_flush_tlb(vcpu);
}

if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
vcpu->arch.efer = vmcs12->guest_ia32_efer;
if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
vcpu->arch.efer |= (EFER_LMA | EFER_LME);
else
vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
/* Note: modifies VM_ENTRY/EXIT_CONTROLS and GUEST/HOST_IA32_EFER */
vmx_set_efer(vcpu, vcpu->arch.efer);

/*
* This sets GUEST_CR0 to vmcs12->guest_cr0, with possibly a modified
* TS bit (for lazy fpu) and bits which we consider mandatory enabled.
* The CR0_READ_SHADOW is what L2 should have expected to read given
* the specifications by L1; It's not enough to take
* vmcs12->cr0_read_shadow because on our cr0_guest_host_mask we we
* have more bits than L1 expected.
*/
vmx_set_cr0(vcpu, vmcs12->guest_cr0);
vmcs_writel(CR0_READ_SHADOW, nested_read_cr0(vmcs12));

vmx_set_cr4(vcpu, vmcs12->guest_cr4);
vmcs_writel(CR4_READ_SHADOW, nested_read_cr4(vmcs12));

/* shadow page tables on either EPT or shadow page tables */
kvm_set_cr3(vcpu, vmcs12->guest_cr3);
kvm_mmu_reset_context(vcpu);

kvm_register_write(vcpu, VCPU_REGS_RSP, vmcs12->guest_rsp);
kvm_register_write(vcpu, VCPU_REGS_RIP, vmcs12->guest_rip);
}

static int vmx_check_intercept(struct kvm_vcpu *vcpu,
struct x86_instruction_info *info,
enum x86_intercept_stage stage)
Expand Down

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