linux-kernel - VMX HOST_RIP target alignment

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 17 Nov 2022 23:46:09 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jpoimboe@...nel.org,
        pbonzini@...hat.com, x86@...nel.org
Subject: VMX HOST_RIP target alignment

One of the side effects of fixing retbleed for VMX was demoting
HOST_RIP target from honorable function to a lowly label:

	-SYM_FUNC_START(vmx_vmexit)
	+SYM_INNER_LABEL(vmx_vmexit, SYM_L_GLOBAL)

ffffffff81243c49:       0f 01 c2                vmlaunch
ffffffff81243c4c:       e9 a7 00 00 00          jmp    ffffffff81243cf8 <vmx_vmexit+0xa7>

ffffffff81243c51 <vmx_vmexit>:
ffffffff81243c51:       50                      push   rax

Now I've never measured VM exit latency but is it important to align it
at 16 bytes like Intel recommends for functions?

	vmalexey