Changing the VMCS12 layout breaks save/restore compatibility with
older kvm releases.
Google has been saving/restoring nested VMX state based on the v4.0
layout. There are no other known users of the
KVM_{GET,SET}_NESTED_STATE ioctls, since those ioctls have not yet
been accepted upstream.
This change reverts the discontinuities introduced in v4.12 and v4.14.
Fixes: c5f983f6e8455 ("nVMX: Implement emulated Page Modification Logging")
Fixes: 27c42a1bb8674 ("KVM: nVMX: Enable VMFUNC for the L1 hypervisor")
Fixes: 41ab93727467c ("KVM: nVMX: Emulate EPTP switching for the L1 hypervisor")
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cd273f7926ef..41f9f932de54 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -242,7 +242,11 @@ struct shared_msr_entry {
* underlying hardware which will be used to run L2.
* This structure is packed to ensure that its layout is identical across
* machines (necessary for live migration).
- * If there are changes in this struct, VMCS12_REVISION must be changed.
+ *
+ * IMPORTANT: Changing the layout of existing fields in this structure
+ * will break save/restore compatibility with older kvm releases. When
+ * adding new fields, either use space in the reserved padding* arrays
+ * or add the new fields to the end of the structure.
*/
typedef u64 natural_width;
struct __packed vmcs12 {
@@ -265,17 +269,14 @@ struct __packed vmcs12 {
u64 virtual_apic_page_addr;
u64 apic_access_addr;
u64 posted_intr_desc_addr;
- u64 vm_function_control;
u64 ept_pointer;
u64 eoi_exit_bitmap0;
u64 eoi_exit_bitmap1;
u64 eoi_exit_bitmap2;
u64 eoi_exit_bitmap3;
- u64 eptp_list_address;
u64 xss_exit_bitmap;
u64 guest_physical_address;
u64 vmcs_link_pointer;
- u64 pml_address;
u64 guest_ia32_debugctl;
u64 guest_ia32_pat;
u64 guest_ia32_efer;
@@ -288,7 +289,10 @@ struct __packed vmcs12 {
u64 host_ia32_pat;
u64 host_ia32_efer;
u64 host_ia32_perf_global_ctrl;
- u64 padding64[8]; /* room for future expansion */
+ u64 vm_function_control;
+ u64 eptp_list_address;
+ u64 pml_address;
+ u64 padding64[5]; /* room for future expansion */
/*
* To allow migration of L1 (complete with its L2 guests) between
* machines of different natural widths (32 or 64 bit), we cannot have
@@ -397,7 +401,6 @@ struct __packed vmcs12 {
u16 guest_ldtr_selector;
u16 guest_tr_selector;
u16 guest_intr_status;
- u16 guest_pml_index;
u16 host_es_selector;
u16 host_cs_selector;
u16 host_ss_selector;
@@ -405,12 +408,16 @@ struct __packed vmcs12 {
u16 host_fs_selector;
u16 host_gs_selector;
u16 host_tr_selector;
+ u16 guest_pml_index;
};
/*
* VMCS12_REVISION is an arbitrary id that should be changed if the content or
* layout of struct vmcs12 is changed. MSR_IA32_VMX_BASIC returns this id, and
* VMPTRLD verifies that the VMCS region that L1 is loading contains this id.
+ *
+ * IMPORTANT: Changing this value will break save/restore compatibility with
+ * older kvm releases.
*/
#define VMCS12_REVISION 0x11e57ed0
@@ -747,7 +754,6 @@ static const unsigned short vmcs_field_to_offset_table[] = {
FIELD(GUEST_LDTR_SELECTOR, guest_ldtr_selector),
FIELD(GUEST_TR_SELECTOR, guest_tr_selector),
FIELD(GUEST_INTR_STATUS, guest_intr_status),
- FIELD(GUEST_PML_INDEX, guest_pml_index),
FIELD(HOST_ES_SELECTOR, host_es_selector),
FIELD(HOST_CS_SELECTOR, host_cs_selector),
FIELD(HOST_SS_SELECTOR, host_ss_selector),
@@ -755,6 +761,7 @@ static const unsigned short vmcs_field_to_offset_table[] = {
FIELD(HOST_FS_SELECTOR, host_fs_selector),
FIELD(HOST_GS_SELECTOR, host_gs_selector),
FIELD(HOST_TR_SELECTOR, host_tr_selector),
+ FIELD(GUEST_PML_INDEX, guest_pml_index),
FIELD64(IO_BITMAP_A, io_bitmap_a),
FIELD64(IO_BITMAP_B, io_bitmap_b),
FIELD64(MSR_BITMAP, msr_bitmap),
@@ -765,17 +772,14 @@ static const unsigned short vmcs_field_to_offset_table[] = {
FIELD64(VIRTUAL_APIC_PAGE_ADDR, virtual_apic_page_addr),
FIELD64(APIC_ACCESS_ADDR, apic_access_addr),
FIELD64(POSTED_INTR_DESC_ADDR, posted_intr_desc_addr),
- FIELD64(VM_FUNCTION_CONTROL, vm_function_control),
FIELD64(EPT_POINTER, ept_pointer),
FIELD64(EOI_EXIT_BITMAP0, eoi_exit_bitmap0),
FIELD64(EOI_EXIT_BITMAP1, eoi_exit_bitmap1),
FIELD64(EOI_EXIT_BITMAP2, eoi_exit_bitmap2),
FIELD64(EOI_EXIT_BITMAP3, eoi_exit_bitmap3),
- FIELD64(EPTP_LIST_ADDRESS, eptp_list_address),
FIELD64(XSS_EXIT_BITMAP, xss_exit_bitmap),
FIELD64(GUEST_PHYSICAL_ADDRESS, guest_physical_address),
FIELD64(VMCS_LINK_POINTER, vmcs_link_pointer),
- FIELD64(PML_ADDRESS, pml_address),
FIELD64(GUEST_IA32_DEBUGCTL, guest_ia32_debugctl),
FIELD64(GUEST_IA32_PAT, guest_ia32_pat),
FIELD64(GUEST_IA32_EFER, guest_ia32_efer),
@@ -788,6 +792,9 @@ static const unsigned short vmcs_field_to_offset_table[] = {
FIELD64(HOST_IA32_PAT, host_ia32_pat),
FIELD64(HOST_IA32_EFER, host_ia32_efer),
FIELD64(HOST_IA32_PERF_GLOBAL_CTRL, host_ia32_perf_global_ctrl),
+ FIELD64(VM_FUNCTION_CONTROL, vm_function_control),
+ FIELD64(EPTP_LIST_ADDRESS, eptp_list_address),
+ FIELD64(PML_ADDRESS, pml_address),
FIELD(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control),
FIELD(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control),
FIELD(EXCEPTION_BITMAP, exception_bitmap),
--
2.17.0.441.gb46fe60e1d-goog
