qubes-linux-utils

Author SHA1 Message Date

Author	SHA1	Message	Date
Patrick Schleizer	8821906186	qubes-kernel-vm-support.postinst run update-grub https://github.com/QubesOS/qubes-issues/issues/5212	5 years ago
Marek Marczykowski-Górecki	de2150e3d3	Add xen_scrub_pages=0 kernel option only if initramfs was rebuilt Rebuild initramfs on package upgrade (already done for Debian previously) and store 1 into /var/lib/qubes/initramfs-updated. Then, only add xen_scrub_pages=0 kernel option if /var/lib/qubes/initramfs-updated is there (with "1" or greater number). This way, if initramfs rebuild doesn't happen for any reason, xen_scrub_pages=0 will not be added. Fixes `456fe99` "Disable scrubbing memory pages during initial balloon down" QubesOS/qubes-issues#1963	5 years ago
Marek Marczykowski-Górecki	456fe99fa6	Disable scrubbing memory pages during initial balloon down Balloon driver scrub memory page before giving it back to the hypervisor. Normally this is a good thing, to avoid leaking VM's memory data into Xen and other domains. But during initial startup when maxmem is bigger than initial memory, on HVM and PVH, Populate-on-Demand (PoD) is in use. This means every page on initial balloon down needs to be first mapped by Xen into VM's memory (as it wasn't populated before - and in fact didn't have any data), scrubbed by the kernel and then given back to Xen. This is great waste of time. Such operation with default settings (initial memory 400M, maxmem 4000M) can take few seconds, delaying every VM startup (including DispVM). In extreme situation, when running inside nested virtualization, the effect is much worse. Avoid this problem by disabling memory scrubbing during initial boot, and re-enable it as soon as user space kicks in - in initramfs, before mounting root filesystem, to be sure it's enabled before memory contains any kind of secrets. This commit handle only one case - when kernel in managed by the VM itself. It is critical to enable initramfs module whenever xen_scrub_pages=0 kernel option is given, so make them depend on the same condition and ship them in the same package. Fixes QubesOS/qubes-issues#1963	5 years ago

Patrick Schleizer

8821906186

qubes-kernel-vm-support.postinst run update-grub

https://github.com/QubesOS/qubes-issues/issues/5212

Marek Marczykowski-Górecki

de2150e3d3

Add xen_scrub_pages=0 kernel option only if initramfs was rebuilt

Rebuild initramfs on package upgrade (already done for Debian
previously) and store 1 into /var/lib/qubes/initramfs-updated. Then,
only add xen_scrub_pages=0 kernel option if
/var/lib/qubes/initramfs-updated is there (with "1" or greater number).
This way, if initramfs rebuild doesn't happen for any reason,
xen_scrub_pages=0 will not be added.

Fixes 456fe99 "Disable scrubbing memory pages during initial balloon down"
QubesOS/qubes-issues#1963

Marek Marczykowski-Górecki

456fe99fa6

Disable scrubbing memory pages during initial balloon down

Balloon driver scrub memory page before giving it back to the
hypervisor. Normally this is a good thing, to avoid leaking VM's memory
data into Xen and other domains. But during initial startup when maxmem
is bigger than initial memory, on HVM and PVH, Populate-on-Demand (PoD) is in use.
This means every page on initial balloon down needs to be first mapped
by Xen into VM's memory (as it wasn't populated before - and in fact
didn't have any data), scrubbed by the kernel and then given back to
Xen. This is great waste of time. Such operation with default settings
(initial memory 400M, maxmem 4000M) can take few seconds, delaying every
VM startup (including DispVM). In extreme situation, when running inside
nested virtualization, the effect is much worse.

Avoid this problem by disabling memory scrubbing during initial boot,
and re-enable it as soon as user space kicks in - in initramfs, before
mounting root filesystem, to be sure it's enabled before memory contains
any kind of secrets.

This commit handle only one case - when kernel in managed by the VM
itself. It is critical to enable initramfs module whenever
xen_scrub_pages=0 kernel option is given, so make them depend on the
same condition and ship them in the same package.

Fixes QubesOS/qubes-issues#1963

3 Commits (master)