CVS commit: src

["Maxime Villard" <maxv%netbsd.org@localhost>]

Module Name:    src
Committed By:   maxv
Date:           Thu Feb 14 14:30:20 UTC 2019

Modified Files:
        src/lib/libnvmm: libnvmm_x86.c
        src/sys/dev/nvmm/x86: nvmm_x86.h nvmm_x86_svm.c nvmm_x86_vmx.c

Log Message:
Harmonize the handling of the CPL between AMD and Intel.

AMD has a separate guest CPL field, because on AMD, the SYSCALL/SYSRET
instructions do not force SS.DPL to predefined values. On Intel they do,
so the CPL on Intel is just the guest's SS.DPL value.

Even though technically possible on AMD, there is no sane reason for a
guest kernel to set a non-three SS.DPL, doing that would mess up several
common segmentation practices and wouldn't be compatible with Intel.

So, force the Intel behavior on AMD, by always setting SS.DPL<=>CPL.
Remove the now unused CPL field from nvmm_x64_state::misc[]. This actually
increases performance on AMD: to detect interrupt windows the virtualizer
has to modify some fields of misc[], and because CPL was there, we had to
flush the SEG set of the VMCB cache. Now there is no flush necessary.

While here remove the CPL check for XSETBV on Intel, contrary to AMD
Intel checks the CPL before the intercept, so if we receive an XSETBV
VMEXIT, we are certain that it was executed at CPL=0 in the guest. By the
way my check was wrong in the first place, it was reading SS.RPL instead
of SS.DPL.


To generate a diff of this commit:
cvs rdiff -u -r1.21 -r1.22 src/lib/libnvmm/libnvmm_x86.c
cvs rdiff -u -r1.4 -r1.5 src/sys/dev/nvmm/x86/nvmm_x86.h
cvs rdiff -u -r1.22 -r1.23 src/sys/dev/nvmm/x86/nvmm_x86_svm.c
cvs rdiff -u -r1.2 -r1.3 src/sys/dev/nvmm/x86/nvmm_x86_vmx.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.