Re: [PATCH 1/3] [RFC V3] KVM: X86: Memory ROE documentation

[Randy Dunlap <rdunlap@infradead.org>]

On 07/19/2018 02:38 PM, Ahmed Abd El Mawgood wrote:

>  Documentation/virtual/kvm/hypercalls.txt | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt
> index a890529c63ed..a9db68adb7c9 100644
> --- a/Documentation/virtual/kvm/hypercalls.txt
> +++ b/Documentation/virtual/kvm/hypercalls.txt
> @@ -121,3 +121,17 @@ compute the CLOCK_REALTIME for its clock, at the same instant.
>  
>  Returns KVM_EOPNOTSUPP if the host does not use TSC clocksource,
>  or if clock type is different than KVM_CLOCK_PAIRING_WALLCLOCK.
> +
> +7. KVM_HC_HMROE
> +----------------
> +Architecture: x86
> +Status: active
> +Purpose: Hypercall used to apply Read-Only Enforcement to guest pages
> +Usage:
> +     a0: start address of page that should be protected.

Is this done one page per call?  No grouping, no multiple pages?

> +
> +This hypercall lets a guest kernel to have part of its read/write memory

                  lets a guest kernel have part of

> +converted into read-only.  This action is irreversible. KVM_HC_HMROE can
> +not be triggered from guest Ring 3 (user mode). The reason is that user
> +mode malicious software can make use of it enforce read only protection on

                               make use of it to enforce

> +an arbitrary memory page thus crashing the kernel.
> 


-- 
~Randy