Guest may not use INVEPT instruction after enabling any of bits 2:0 from
0 to 1 of a present EPT entry, then the shadow EPT entry has no chance
to sync guest EPT entry. According to the SDM,
"""
Software may use the INVEPT instruction after modifying a present EPT
paging-structure entry (see Section 28.2.2) to change any of the
privilege bits 2:0 from 0 to 1.1 Failure to do so may cause an EPT
violation that would not otherwise occur. Because an EPT violation
invalidates any mappings that would be used by the access that caused
the EPT violation (see Section 28.3.3.1), an EPT violation will not
recur if the original access is performed again, even if the INVEPT
instruction is not executed.
"""
Sync the afterthought of privilege bits from guest EPT entry to shadow
EPT entry to cover above case.
Tracked-On: #5923
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
MSR_IA32_VMX_EPT_VPID_CAP is 64 bits. Using 32 bits MACROs with it may
cause the bit expression wrong.
Unify the MSR_IA32_VMX_EPT_VPID_CAP operation with 64 bits definition.
Tracked-On: #5923
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
get_ept_entry() actually returns the EPTP of a VM. So rename it to
get_eptp() for readability.
Tracked-On: #5923
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
generate_shadow_ept_entry() didn't verify the correctness of the requested
guest EPT mapping. That might leak host memory access to L2 VM.
To simplify the implementation of the guest EPT audit, hide capabilities
'map 2-Mbyte page' and 'map 1-Gbyte page' from L1 VM. In addition,
minimize the attribute bits of EPT entry when create a shadow EPT entry.
Also, for invalid requested mapping address, reflect the EPT_VIOLATION to
L1 VM.
Here, we have some TODOs:
1) Enable large page support in generate_shadow_ept_entry()
2) Evaluate if need to emulate the invalid GPA access of L2 in HV directly.
3) Minimize EPT entry attributes.
Tracked-On: #5923
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
L1 VM changes the guest EPT and do INVEPT to invalidate the previous
TLB cache of EPT entries. The shadow EPT replies on INVEPT instruction
to do the update.
The target shadow EPTs can be found according to the 'type' of INVEPT.
Here are two types and their target shadow EPT,
1) Single-context invalidation
Get the EPTP from the INVEPT descriptor. Then find the target
shadow EPT.
2) Global invalidation
All shadow EPTs of the L1 VM.
The INVEPT emulation handler invalidate all the EPT entries of the
target shadow EPTs.
Tracked-On: #5923
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
When a shadow EPT is not used anymore, its resources need to be
released.
free_sept_table() is introduced to walk the whole shadow EPT table and
free the pagetable pages.
Please note, the PML4E page of shadow EPT is not freed by
free_sept_table() as it still be used to present a shadow EPT pointer.
Tracked-On: #5923
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
With shadow EPT, the hypervisor walks through guest EPT table:
* If the entry is not present in guest EPT, ACRN injects EPT_VIOLATION
to L1 VM and resumes to L1 VM.
* If the entry is present in guest EPT, do the EPT_MISCONFIG check.
Inject EPT_MISCONFIG to L1 VM if the check failed.
* If the entry is present in guest EPT, do permission check.
Reflect EPT_VIOLATION to L1 VM if the check failed.
* If the entry is present in guest EPT but shadow EPT entry is not
present, create the shadow entry and resumes to L2 VM.
* If the entry is present in guest EPT but the GPA in the entry is
invalid, injects EPT_VIOLATION to L1 VM and resumes L1 VM.
Tracked-On: #5923
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
'struct nept_desc' is used to associate guest EPTP with a shadow EPTP.
It's created in the first reference and be freed while no reference.
The life cycle seems like,
While guest VMCS VMX_EPT_POINTER_FULL is changed, the 'struct nept_desc'
of the new guest EPTP is referenced; the 'struct nept_desc' of the old
guest EPTP is dereferenced.
While guest VMCS be cleared(by VMCLEAR in L1 VM), the 'struct nept_desc'
of the old guest EPTP is dereferenced.
While a new guest VMCS be loaded(by VMPTRLD in L1 VM), the 'struct
nept_desc' of the new guest EPTP is referenced. The 'struct nept_desc'
of the old guest EPTP is dereferenced.
Tracked-On: #5923
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
To shadow guest EPT, the hypervisor needs construct a shadow EPT for each
guest EPT. The key to associate a shadow EPT and a guest EPT is the EPTP
(EPT pointer). This patch provides following structure to do the association.
struct nept_desc {
/*
* A shadow EPTP.
* The format is same with 'EPT pointer' in VMCS.
* Its PML4 address field is a HVA of the hypervisor.
*/
uint64_t shadow_eptp;
/*
* An guest EPTP configured by L1 VM.
* The format is same with 'EPT pointer' in VMCS.
* Its PML4 address field is a GPA of the L1 VM.
*/
uint64_t guest_eptp;
uint32_t ref_count;
};
Due to lack of dynamic memory allocation of the hypervisor, a array
nept_bucket of type 'struct nept_desc' is introduced to store those
association information. A guest EPT might be shared between different
L2 vCPUs, so this patch provides several functions to handle the
reference of the structure.
Interface get_shadow_eptp() also is introduced. To find the shadow EPTP
of a specified guest EPTP.
Tracked-On: #5923
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
Shadow EPT uses lots of pages to construct the shadow page table. To
utilize the memory more efficient, a page poll sept_page_pool is
introduced.
For simplicity, total platform RAM size is considered to calculate the
memory needed for shadow page tables. This is not an accurate upper
bound. This can satisfy typical use-cases where there is not a lot
of overcommitment and sharing of memory between L2 VMs.
Memory of the pool is marked as reserved from E820 table in early stage.
Tracked-On: #5923
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
invvpid and invept instructions cause VM exits unconditionally.
For initial support, we pass all the instruction operands as is
to the pCPU.
Tracked-On: #5923
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
