Private bug reported:
Placeholder. Need to change Precise arch/x86/kernel/kvm/* from:
if (ibrs_enabled && (svm->spec_ctrl != SPEC_CTRL_IBRS))
wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
<SNIP>
if (ibrs_enabled) {
rdmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
if (svm->spec_ctrl != SPEC_CTRL_IBRS)
wrmsrl(MSR_IA32_SPEC_CTRL, SPEC_CTRL_IBRS);
}
to:
x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
<SNIP>
x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl);
to properly set and restore the MSR.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Affects: linux (Ubuntu Precise)
Importance: Undecided
Status: New
** Information type changed from Public to Private
** Also affects: linux (Ubuntu Precise)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1834635
Title:
x86/speculation: SPEC_CTRL MSR not properly set/restored on
VMENTER/VMEXIT
Status in linux package in Ubuntu:
New
Status in linux source package in Precise:
New
Bug description:
Placeholder. Need to change Precise arch/x86/kernel/kvm/* from:
if (ibrs_enabled && (svm->spec_ctrl != SPEC_CTRL_IBRS))
wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
<SNIP>
if (ibrs_enabled) {
rdmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
if (svm->spec_ctrl != SPEC_CTRL_IBRS)
wrmsrl(MSR_IA32_SPEC_CTRL, SPEC_CTRL_IBRS);
}
to:
x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
<SNIP>
x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl);
to properly set and restore the MSR.
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