Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1232644

Re: [PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific vpid

Show all headers | View raw

On 24/09/2015 18:12, Bandan Das wrote:
> Not sure myself what's the right thing to do but this may be undesirable
> in a nested environment. Assuming the processor supports global invalidation
> only, this seems like a easy way for the nested guest to invalidate *all*
> mappings - even the L1 specific mappings.

It's not a great thing but it's already what happens if you do a global
INVEPT (it calls vmx_flush_tlb, which results in a global INVVPID if the
single-context variant is not supported).

Even without nested virt a single guest could slow down all other guests
just by triggering frequent TLB flushes (e.g. by moving around a ROM BAR
thousands of times per second).

It would help to know _which_ processors actually don't support
single-context INVVPIDs...

Paolo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific vpid Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-23 12:30 +0200
  Re: [PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific vpid Bandan Das <bsd@redhat.com> - 2015-09-24 18:20 +0200
    Re: [PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific  vpid Wanpeng Li <wanpeng.li@hotmail.com> - 2015-09-25 05:10 +0200
    Re: [PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific  vpid Paolo Bonzini <pbonzini@redhat.com> - 2015-09-25 10:10 +0200

csiph-web