From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ahmed Abd El Mawgood Subject: [RESEND PATCH V8 04/11] KVM: Document Memory ROE Date: Mon, 21 Jan 2019 01:39:33 +0200 Message-Id: <20190120233940.15282-5-ahmedsoliman@mena.vt.edu> In-Reply-To: <20190120233940.15282-1-ahmedsoliman@mena.vt.edu> References: <20190120233940.15282-1-ahmedsoliman@mena.vt.edu> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: Paolo Bonzini , rkrcmar@redhat.com, Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, ahmedsoliman0x666@gmail.com, ovich00@gmail.com, kernel-hardening@lists.openwall.com, nigel.edwards@hpe.com, Boris Lukashev , Igor Stoppa Cc: Ahmed Abd El Mawgood List-ID: ROE version documented here is implemented in the next 2 patches Signed-off-by: Ahmed Abd El Mawgood --- 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