On 22/04/21 19:57, Sean Christopherson wrote:
On Thu, Apr 22, 2021, Paolo Bonzini wrote:
On 22/04/21 05:04, Sean Christopherson wrote:
Load the per-cpu GS.base for 32-bit build by building a temporary GDT
and loading a "real" segment. Using MSR_GS_BASE is wrong and broken,
it's a 64-bit only MSR and does not exist on 32-bit CPUs. The current
code works only because 32-bit KVM VMX incorrectly disables interception
of MSR_GS_BASE, and no one runs KVM on an actual 32-bit physical CPU,
i.e. the MSR exists in hardware and so everything "works".
32-bit KVM SVM is not buggy and correctly injects #GP on the WRMSR, i.e.
the tests have never worked on 32-bit SVM.
Hmm, this breaks task switch. But setting up separate descriptors is
not hard:
Much better.
Using %ebx crushes the mbi_bootinfo pointer. The easiest fix is to use %edx or
%ecx.
+ mov (%ebx), %ebx
No need to load the address into a reg, just drop the "$" above and encode
"mov [imm32], <reg>".
Yep, I had already fixed more or less the same things (plus the task
gate TSS setup, which must not hardcode GS to 0x10; no idea how it
worked before) before seeing your mail. I sent the result to the
mailing list.
Paolo
