mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 08:40:53 +07:00
3c603573d2
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200713114719.33839-1-grandmaster@al2klimov.de
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
243 lines
7.7 KiB
ReStructuredText
243 lines
7.7 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
==========
|
|
Nested VMX
|
|
==========
|
|
|
|
Overview
|
|
---------
|
|
|
|
On Intel processors, KVM uses Intel's VMX (Virtual-Machine eXtensions)
|
|
to easily and efficiently run guest operating systems. Normally, these guests
|
|
*cannot* themselves be hypervisors running their own guests, because in VMX,
|
|
guests cannot use VMX instructions.
|
|
|
|
The "Nested VMX" feature adds this missing capability - of running guest
|
|
hypervisors (which use VMX) with their own nested guests. It does so by
|
|
allowing a guest to use VMX instructions, and correctly and efficiently
|
|
emulating them using the single level of VMX available in the hardware.
|
|
|
|
We describe in much greater detail the theory behind the nested VMX feature,
|
|
its implementation and its performance characteristics, in the OSDI 2010 paper
|
|
"The Turtles Project: Design and Implementation of Nested Virtualization",
|
|
available at:
|
|
|
|
https://www.usenix.org/events/osdi10/tech/full_papers/Ben-Yehuda.pdf
|
|
|
|
|
|
Terminology
|
|
-----------
|
|
|
|
Single-level virtualization has two levels - the host (KVM) and the guests.
|
|
In nested virtualization, we have three levels: The host (KVM), which we call
|
|
L0, the guest hypervisor, which we call L1, and its nested guest, which we
|
|
call L2.
|
|
|
|
|
|
Running nested VMX
|
|
------------------
|
|
|
|
The nested VMX feature is disabled by default. It can be enabled by giving
|
|
the "nested=1" option to the kvm-intel module.
|
|
|
|
No modifications are required to user space (qemu). However, qemu's default
|
|
emulated CPU type (qemu64) does not list the "VMX" CPU feature, so it must be
|
|
explicitly enabled, by giving qemu one of the following options:
|
|
|
|
- cpu host (emulated CPU has all features of the real CPU)
|
|
|
|
- cpu qemu64,+vmx (add just the vmx feature to a named CPU type)
|
|
|
|
|
|
ABIs
|
|
----
|
|
|
|
Nested VMX aims to present a standard and (eventually) fully-functional VMX
|
|
implementation for the a guest hypervisor to use. As such, the official
|
|
specification of the ABI that it provides is Intel's VMX specification,
|
|
namely volume 3B of their "Intel 64 and IA-32 Architectures Software
|
|
Developer's Manual". Not all of VMX's features are currently fully supported,
|
|
but the goal is to eventually support them all, starting with the VMX features
|
|
which are used in practice by popular hypervisors (KVM and others).
|
|
|
|
As a VMX implementation, nested VMX presents a VMCS structure to L1.
|
|
As mandated by the spec, other than the two fields revision_id and abort,
|
|
this structure is *opaque* to its user, who is not supposed to know or care
|
|
about its internal structure. Rather, the structure is accessed through the
|
|
VMREAD and VMWRITE instructions.
|
|
Still, for debugging purposes, KVM developers might be interested to know the
|
|
internals of this structure; This is struct vmcs12 from arch/x86/kvm/vmx.c.
|
|
|
|
The name "vmcs12" refers to the VMCS that L1 builds for L2. In the code we
|
|
also have "vmcs01", the VMCS that L0 built for L1, and "vmcs02" is the VMCS
|
|
which L0 builds to actually run L2 - how this is done is explained in the
|
|
aforementioned paper.
|
|
|
|
For convenience, we repeat the content of struct vmcs12 here. If the internals
|
|
of this structure changes, this can break live migration across KVM versions.
|
|
VMCS12_REVISION (from vmx.c) should be changed if struct vmcs12 or its inner
|
|
struct shadow_vmcs is ever changed.
|
|
|
|
::
|
|
|
|
typedef u64 natural_width;
|
|
struct __packed vmcs12 {
|
|
/* According to the Intel spec, a VMCS region must start with
|
|
* these two user-visible fields */
|
|
u32 revision_id;
|
|
u32 abort;
|
|
|
|
u32 launch_state; /* set to 0 by VMCLEAR, to 1 by VMLAUNCH */
|
|
u32 padding[7]; /* room for future expansion */
|
|
|
|
u64 io_bitmap_a;
|
|
u64 io_bitmap_b;
|
|
u64 msr_bitmap;
|
|
u64 vm_exit_msr_store_addr;
|
|
u64 vm_exit_msr_load_addr;
|
|
u64 vm_entry_msr_load_addr;
|
|
u64 tsc_offset;
|
|
u64 virtual_apic_page_addr;
|
|
u64 apic_access_addr;
|
|
u64 ept_pointer;
|
|
u64 guest_physical_address;
|
|
u64 vmcs_link_pointer;
|
|
u64 guest_ia32_debugctl;
|
|
u64 guest_ia32_pat;
|
|
u64 guest_ia32_efer;
|
|
u64 guest_pdptr0;
|
|
u64 guest_pdptr1;
|
|
u64 guest_pdptr2;
|
|
u64 guest_pdptr3;
|
|
u64 host_ia32_pat;
|
|
u64 host_ia32_efer;
|
|
u64 padding64[8]; /* room for future expansion */
|
|
natural_width cr0_guest_host_mask;
|
|
natural_width cr4_guest_host_mask;
|
|
natural_width cr0_read_shadow;
|
|
natural_width cr4_read_shadow;
|
|
natural_width dead_space[4]; /* Last remnants of cr3_target_value[0-3]. */
|
|
natural_width exit_qualification;
|
|
natural_width guest_linear_address;
|
|
natural_width guest_cr0;
|
|
natural_width guest_cr3;
|
|
natural_width guest_cr4;
|
|
natural_width guest_es_base;
|
|
natural_width guest_cs_base;
|
|
natural_width guest_ss_base;
|
|
natural_width guest_ds_base;
|
|
natural_width guest_fs_base;
|
|
natural_width guest_gs_base;
|
|
natural_width guest_ldtr_base;
|
|
natural_width guest_tr_base;
|
|
natural_width guest_gdtr_base;
|
|
natural_width guest_idtr_base;
|
|
natural_width guest_dr7;
|
|
natural_width guest_rsp;
|
|
natural_width guest_rip;
|
|
natural_width guest_rflags;
|
|
natural_width guest_pending_dbg_exceptions;
|
|
natural_width guest_sysenter_esp;
|
|
natural_width guest_sysenter_eip;
|
|
natural_width host_cr0;
|
|
natural_width host_cr3;
|
|
natural_width host_cr4;
|
|
natural_width host_fs_base;
|
|
natural_width host_gs_base;
|
|
natural_width host_tr_base;
|
|
natural_width host_gdtr_base;
|
|
natural_width host_idtr_base;
|
|
natural_width host_ia32_sysenter_esp;
|
|
natural_width host_ia32_sysenter_eip;
|
|
natural_width host_rsp;
|
|
natural_width host_rip;
|
|
natural_width paddingl[8]; /* room for future expansion */
|
|
u32 pin_based_vm_exec_control;
|
|
u32 cpu_based_vm_exec_control;
|
|
u32 exception_bitmap;
|
|
u32 page_fault_error_code_mask;
|
|
u32 page_fault_error_code_match;
|
|
u32 cr3_target_count;
|
|
u32 vm_exit_controls;
|
|
u32 vm_exit_msr_store_count;
|
|
u32 vm_exit_msr_load_count;
|
|
u32 vm_entry_controls;
|
|
u32 vm_entry_msr_load_count;
|
|
u32 vm_entry_intr_info_field;
|
|
u32 vm_entry_exception_error_code;
|
|
u32 vm_entry_instruction_len;
|
|
u32 tpr_threshold;
|
|
u32 secondary_vm_exec_control;
|
|
u32 vm_instruction_error;
|
|
u32 vm_exit_reason;
|
|
u32 vm_exit_intr_info;
|
|
u32 vm_exit_intr_error_code;
|
|
u32 idt_vectoring_info_field;
|
|
u32 idt_vectoring_error_code;
|
|
u32 vm_exit_instruction_len;
|
|
u32 vmx_instruction_info;
|
|
u32 guest_es_limit;
|
|
u32 guest_cs_limit;
|
|
u32 guest_ss_limit;
|
|
u32 guest_ds_limit;
|
|
u32 guest_fs_limit;
|
|
u32 guest_gs_limit;
|
|
u32 guest_ldtr_limit;
|
|
u32 guest_tr_limit;
|
|
u32 guest_gdtr_limit;
|
|
u32 guest_idtr_limit;
|
|
u32 guest_es_ar_bytes;
|
|
u32 guest_cs_ar_bytes;
|
|
u32 guest_ss_ar_bytes;
|
|
u32 guest_ds_ar_bytes;
|
|
u32 guest_fs_ar_bytes;
|
|
u32 guest_gs_ar_bytes;
|
|
u32 guest_ldtr_ar_bytes;
|
|
u32 guest_tr_ar_bytes;
|
|
u32 guest_interruptibility_info;
|
|
u32 guest_activity_state;
|
|
u32 guest_sysenter_cs;
|
|
u32 host_ia32_sysenter_cs;
|
|
u32 padding32[8]; /* room for future expansion */
|
|
u16 virtual_processor_id;
|
|
u16 guest_es_selector;
|
|
u16 guest_cs_selector;
|
|
u16 guest_ss_selector;
|
|
u16 guest_ds_selector;
|
|
u16 guest_fs_selector;
|
|
u16 guest_gs_selector;
|
|
u16 guest_ldtr_selector;
|
|
u16 guest_tr_selector;
|
|
u16 host_es_selector;
|
|
u16 host_cs_selector;
|
|
u16 host_ss_selector;
|
|
u16 host_ds_selector;
|
|
u16 host_fs_selector;
|
|
u16 host_gs_selector;
|
|
u16 host_tr_selector;
|
|
};
|
|
|
|
|
|
Authors
|
|
-------
|
|
|
|
These patches were written by:
|
|
- Abel Gordon, abelg <at> il.ibm.com
|
|
- Nadav Har'El, nyh <at> il.ibm.com
|
|
- Orit Wasserman, oritw <at> il.ibm.com
|
|
- Ben-Ami Yassor, benami <at> il.ibm.com
|
|
- Muli Ben-Yehuda, muli <at> il.ibm.com
|
|
|
|
With contributions by:
|
|
- Anthony Liguori, aliguori <at> us.ibm.com
|
|
- Mike Day, mdday <at> us.ibm.com
|
|
- Michael Factor, factor <at> il.ibm.com
|
|
- Zvi Dubitzky, dubi <at> il.ibm.com
|
|
|
|
And valuable reviews by:
|
|
- Avi Kivity, avi <at> redhat.com
|
|
- Gleb Natapov, gleb <at> redhat.com
|
|
- Marcelo Tosatti, mtosatti <at> redhat.com
|
|
- Kevin Tian, kevin.tian <at> intel.com
|
|
- and others.
|