On 4/19/2023 11:08 AM, Binbin Wu wrote:
On 4/19/2023 10:30 AM, Chao Gao wrote:
On Tue, Apr 04, 2023 at 09:09:21PM +0800, Binbin Wu wrote:
Introduce a new interface untag_addr() to kvm_x86_ops to untag the
metadata
>from linear address. Implement LAM version in VMX and dummy version
in SVM.
When enabled feature like Intel Linear Address Masking or AMD Upper
Address Ignore, linear address may be tagged with metadata. Linear
address should be checked for modified canonicality and untagged in
instrution emulations or vmexit handlings if LAM or UAI is applicable.
Introduce untag_addr() to kvm_x86_ops to hide the code related to
vendor
specific details.
- For VMX, LAM version is implemented.
LAM has a modified canonical check when applicable:
* LAM_S48 : [ 1 ][ metadata ][ 1 ]
63 47
* LAM_U48 : [ 0 ][ metadata ][ 0 ]
63 47
* LAM_S57 : [ 1 ][ metadata ][ 1 ]
63 56
* LAM_U57 + 5-lvl paging : [ 0 ][ metadata ][ 0 ]
63 56
* LAM_U57 + 4-lvl paging : [ 0 ][ metadata ][ 0...0 ]
63 56..47
If LAM is applicable to certain address, untag the metadata bits and
replace them with the value of bit 47 (LAM48) or bit 56 (LAM57).
Later
the untagged address will do legacy canonical check. So that LAM
canonical
check and mask can be covered by "untag + legacy canonical check".
For cases LAM is not applicable, 'flags' is passed to the interface
to skip untag.
The "flags" can be dropped. Callers can simply skip the call of
.untag_addr().
OK.
The "flags" was added for proof of future if such kind of untag is
also adopted in svm for AMD.
The cases to skip untag are different on the two vendor platforms.
But still, it is able to get the information in __linearize(), I will
drop the parameter.
Have a second thought, the flags is still needed to pass to vmx/svm.
If both implementions set the skip untag flag (SKIP_UNTAG_VMX |
SKIP_UNTAG_SVM)
or neither sets the skip untag flag, __linearize() can decide to call
.untag_addr() or not.
However, in some case, if only one of the implementation need to set the
skip untag for itself,
in __linearize(), there is no enough information to tell whether to skip
the untag or not.
- For SVM, add a dummy version to do nothing, but return the original
address.
Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
Tested-by: Xuelian Guo <xuelian.guo@xxxxxxxxx>
---
[...]
