Date: Fri, 7 Dec 2018 14:47:57 +0200 From: Ahmed Abd El Mawgood <ahmedsoliman@...a.vt.edu> To: Paolo Bonzini <pbonzini@...hat.com>, rkrcmar@...hat.com, Jonathan Corbet <corbet@....net>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, ahmedsoliman0x666@...il.com, ovich00@...il.com, kernel-hardening@...ts.openwall.com, nigel.edwards@....com, Boris Lukashev <blukashev@...pervictus.com>, Igor Stoppa <igor.stoppa@...il.com> Cc: Ahmed Abd El Mawgood <ahmedsoliman@...a.vt.edu> Subject: [PATCH 04/10] KVM: Document Memory ROE ROE version documented here is implemented in the next 2 patches Signed-off-by: Ahmed Abd El Mawgood <ahmedsoliman@...a.vt.edu> --- Documentation/virtual/kvm/hypercalls.txt | 40 ++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt index da24c138c8..a31f316ce6 100644 --- a/Documentation/virtual/kvm/hypercalls.txt +++ b/Documentation/virtual/kvm/hypercalls.txt @@ -141,3 +141,43 @@ a0 corresponds to the APIC ID in the third argument (a2), bit 1 corresponds to the APIC ID a2+1, and so on. Returns the number of CPUs to which the IPIs were delivered successfully. + +7. KVM_HC_ROE +---------------- +Architecture: x86 +Status: active +Purpose: Hypercall used to apply Read-Only Enforcement to guest memory and +registers +Usage 1: + a0: ROE_VERSION + +Returns non-signed number that represents the current version of ROE +implementation current version. + +Usage 2: + + a0: ROE_MPROTECT (requires version >= 1) + a1: Start address aligned to page boundary. + a2: Number of pages to be protected. + +This configuration lets a guest kernel have part of its read/write memory +converted into read-only. This action is irreversible. +Upon successful run, the number of pages protected is returned. + +Usage 3: + a0: ROE_MPROTECT_CHUNK (requires version >= 2) + a1: Start address aligned to page boundary. + a2: Number of bytes to be protected. +This configuration lets a guest kernel have part of its read/write memory +converted into read-only with bytes granularity. ROE_MPROTECT_CHUNK is +relatively slow compared to ROE_MPROTECT. This action is irreversible. +Upon successful run, the number of bytes protected is returned. + +Error codes: + -KVM_ENOSYS: system call being triggered from ring 3 or it is not + implemented. + -EINVAL: error based on given parameters. + +Notes: KVM_HC_ROE can not be triggered from guest Ring 3 (user mode). The +reason is that user mode malicious software can make use of it to enforce read +only protection on an arbitrary memory page thus crashing the kernel. -- 2.19.2
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