Joerg Roedel a13644f3a5 x86/entry/64: Add entry code for #VC handler ... The #VC handler needs special entry code because: 1. It runs on an IST stack 2. It needs to be able to handle nested #VC exceptions To make this work, the entry code is implemented to pretend it doesn't use an IST stack. When entered from user-mode or early SYSCALL entry path it switches to the task stack. If entered from kernel-mode it tries to switch back to the previous stack in the IRET frame. The stack found in the IRET frame is validated first, and if it is not safe to use it for the #VC handler, the code will switch to a fall-back stack (the #VC2 IST stack). From there, it can cause nested exceptions again. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200907131613.12703-46-joro@8bytes.org		2020-09-09 11:33:19 +02:00
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asm	x86/entry/64: Add entry code for #VC handler	2020-09-09 11:33:19 +02:00
uapi/asm	x86/boot/compressed/64: Setup a GHCB-based VC Exception handler	2020-09-07 19:45:25 +02:00