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Enable INVPCID instruction #471
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When running a Linux virtual machine on top of hardware that suffers from meltdown vulnerabilities (i.e., the processor does not advertise the "No Rogue Data Cache Load" bit in the IA32_ARCH_CAPABILITIES MSR), the Linux guest will enable "Kernel Page Table Isolation" (aka KPTI). This has performance impacts because the page tables need to be adjusted on each jump between user mode and kernel mode. The Linux kernel will perform it more efficiently if it has the ability to use the INVPCID instruction. * Add ENABLE_INVPCID for secondary processor-based VM-execution controls * Enable X86_FEATURE_INVPCID support in CPUID Signed-off-by: Wenchao Wang <[email protected]>
hyuan3
approved these changes
Oct 18, 2022
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When running a Linux virtual machine on top of hardware that suffers from meltdown vulnerabilities (i.e., the processor does not advertise the "No Rogue Data Cache Load" bit in the IA32_ARCH_CAPABILITIES MSR), the Linux guest will enable "Kernel Page Table Isolation" (aka KPTI).
This has performance impacts because the page tables need to be adjusted on each jump between user mode and kernel mode. The Linux kernel will perform it more efficiently if it has the ability to use the INVPCID instruction.