From 9d1f0985a77429c6d527077a44b28d43f5906112 Mon Sep 17 00:00:00 2001 From: Stefan Berger Date: Mon, 5 Mar 2018 17:10:01 -0500 Subject: docs: tpm: add VM save/restore example and troubleshooting guide Extend the docs related to TPM with specs related to VM save and restore and a troubleshooting guide for TPM migration. Signed-off-by: Stefan Berger Reviewed-by: Dr. David Alan Gilbert --- docs/specs/tpm.txt | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 106 insertions(+) (limited to 'docs') diff --git a/docs/specs/tpm.txt b/docs/specs/tpm.txt index d1d7157..c230c4c 100644 --- a/docs/specs/tpm.txt +++ b/docs/specs/tpm.txt @@ -200,3 +200,109 @@ crw-------. 1 root root 10, 224 Jul 11 10:11 /dev/tpm0 PCR-00: 35 4E 3B CE 23 9F 38 59 ... ... PCR-23: 00 00 00 00 00 00 00 00 ... + + +=== Migration with the TPM emulator === + +The TPM emulator supports the following types of virtual machine migration: + +- VM save / restore (migration into a file) +- Network migration +- Snapshotting (migration into storage like QoW2 or QED) + +The following command sequences can be used to test VM save / restore. + + +In a 1st terminal start an instance of a swtpm using the following command: + +mkdir /tmp/mytpm1 +swtpm socket --tpmstate dir=/tmp/mytpm1 \ + --ctrl type=unixio,path=/tmp/mytpm1/swtpm-sock \ + --log level=20 --tpm2 + +In a 2nd terminal start the VM: + +qemu-system-x86_64 -display sdl -enable-kvm \ + -m 1024 -boot d -bios bios-256k.bin -boot menu=on \ + -chardev socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock \ + -tpmdev emulator,id=tpm0,chardev=chrtpm \ + -device tpm-tis,tpmdev=tpm0 \ + -monitor stdio \ + test.img + +Verify that the attached TPM is working as expected using applications inside +the VM. + +To store the state of the VM use the following command in the QEMU monitor in +the 2nd terminal: + +(qemu) migrate "exec:cat > testvm.bin" +(qemu) quit + +At this point a file called 'testvm.bin' should exists and the swtpm and QEMU +processes should have ended. + +To test 'VM restore' you have to start the swtpm with the same parameters +as before. If previously a TPM 2 [--tpm2] was saved, --tpm2 must now be +passed again on the command line. + +In the 1st terminal restart the swtpm with the same command line as before: + +swtpm socket --tpmstate dir=/tmp/mytpm1 \ + --ctrl type=unixio,path=/tmp/mytpm1/swtpm-sock \ + --log level=20 --tpm2 + +In the 2nd terminal restore the state of the VM using the additonal +'-incoming' option. + +qemu-system-x86_64 -display sdl -enable-kvm \ + -m 1024 -boot d -bios bios-256k.bin -boot menu=on \ + -chardev socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock \ + -tpmdev emulator,id=tpm0,chardev=chrtpm \ + -device tpm-tis,tpmdev=tpm0 \ + -incoming "exec:cat < testvm.bin" \ + test.img + + +Troubleshooting migration: + +There are several reasons why migration may fail. In case of problems, +please ensure that the command lines adhere to the following rules and, +if possible, that identical versions of QEMU and swtpm are used at all +times. + +VM save and restore: + - QEMU command line parameters should be identical apart from the + '-incoming' option on VM restore + - swtpm command line parameters should be identical + +VM migration to 'localhost': + - QEMU command line parameters should be identical apart from the + '-incoming' option on the destination side + - swtpm command line parameters should point to two different + directories on the source and destination swtpm (--tpmstate dir=...) + (especially if different versions of libtpms were to be used on the + same machine). + +VM migration across the network: + - QEMU command line parameters should be identical apart from the + '-incoming' option on the destination side + - swtpm command line parameters should be identical + +VM Snapshotting: + - QEMU command line parameters should be identical + - swtpm command line parameters should be identical + + +Besides that, migration failure reasons on the swtpm level may include +the following: + + - the versions of the swtpm on the source and destination sides are + incompatible + - downgrading of TPM state may not be supported + - the source and destination libtpms were compiled with different + compile-time options and the destination side refuses to accept the + state + - different migration keys are used on the source and destination side + and the destination side cannot decrypt the migrated state + (swtpm ... --migration-key ... ) -- cgit v1.1