KVA Shadow: Mitigating Meltdown on Windows

On January 3rd, 2018, Microsoft released an advisory and security updates that relate to a new class of discovered hardware vulnerabilities, termed speculative execution side channels, that affect the design methodology and implementation decisions behind many modern microprocessors. This post dives into the technical details of Kernel Virtual Address (KVA) Shadow which is the Windows kernel mitigation for one specific speculative execution side channel: the rogue data cache load vulnerability (CVE-2017-5754, also known as “Meltdown” or “Variant 3”). KVA Shadow is one of the mitigations that is in scope for Microsoft’s recently announced Speculative Execution Side Channel bounty program. It’s important to note that there are several different types of issues that fall under the category of speculative execution side channels, and that different mitigations are required for each type of issue. Additional information about the mitigations that Microsoft has developed for other speculative execution side channel vulnerabilities (“Spectre”), as well as additional background information on this class of issue, can be found here. Please note that the information in this post is current as of the date of this post.[…]

https://blogs.technet.microsoft.com/srd/2018/03/23/kva-shadow-mitigating-meltdown-on-windows/