Thursday, January 3, 2019

Tons of email backlog.

Laptop cleanup. Tons of old junk, notably old video segments for various demos that I no longer need.

CR0 management in KVM

Spent some time trying to understand the solution for Red Hat Bugzilla 1655873 (RHEL8 guest can not run on RHEL6 host (AMD)) as explained in comment 14. The explanation itself is relatively simple, but I wanted to explore the changes made to CR0 intercept over time.

Wei Huang helpfully provides the list of relevant changes in the Linux kernel:

4610c83cdc8b KVM: SVM: Lazy fpu with npt
d225157bc6a4 KVM: SVM: Selective cr0 intercept
888f9f3e0cfa KVM: SVM: Restore unconditional cr0 intercept under npt
bff7827479ed KVM: SVM: Initialize fpu_active in init_vmcb()

Spent a bit of time trying to understand how the EFER.LME processing code in Linux is working.

EFER.LME is defined in Intel's manuals . But the bug is really more related to the fact that CR0 writes are not intercepted, so that internal state is reconstructed at the next VMEXIT, at which point it is reconstructed incorrectly.

There is so much for me to learn about system-level x86... There is so much to learn about KVM and QEMU. So little time.

Expense reports and PayPal

I started filling an expense report for my upcoming trip to Brno (DevConf.cz). I wanted to go back to my bank account logs to check how much had been charged, notably because I noticed that Egencia was charging extra 5 euros charges for every operation they made, and I wanted to make sure that I accounted for that in my report.

That's where I noticed a PayPal repeated payment. This reminded me that this was for a donation to an association that I wanted to cancel. So I found the PayPal email they send me every month for that transaction, and followed the instructions. The instructions did not work, because the repeated transaction did not show up in my PayPal account. So I clicked on the link to the transaction in the email, and I got a 404 (page not found) error. Uh oh. So I searched for transactions on my PayPal account, and none of the transactions showed up! Uh oh again.

Time to call PayPal. Now, that's an experience. You need to click through their web site to get a one-time authentication code! Then you wait. Then they tell you they have nobody and they will call you back, at which point you need to enter your phone number (caller ID anyone?). Then they call you back, but there is actually nobody on the line for another couple of minutes. Then the person goes through the most basic stuff (as usual for phone line support) as if you were a complete idiot. Then they explain that it's my fault because I somehow "misused" the PayPal button the the merchant's web site. Apparently, I somehow entered my credit card there but PayPal did not record it as belonging to my account because I was not logged in, something like that.

Finally, the representative said there was nothing she could do, and suggested I should call the vendor. In short: PayPal has my email address and credit card. They charge me every month and send me an email to my PayPal account email address. But somehow, they can't associate the credit card to my account? Seriously? They send me email with a clickable link to the transaction with results in 404, and the solution to that is talking to the vendor?

So I spent the time explaining the problem again in email. If you ever need to do that, my suggestion is: don't bother. They don't even read your first email. They just auto-reply to it with the same basic "how-to" information from their help page. But you can reply to that, and then they claim they will read your email.

Did I mention you can only send "mail" through their web form, which automatically disconnects you after a few minutes, and returns to the main page, discarding all your changes without even asking. So say you decide to postpone things to check an email or look something up. You then go back to the page, and it's gone. So you search and you search and you don't find it. So you type your email again. A few minutes later, that second email draft has vaporized into ether again. That's when you realize that it's really PayPal actively destroying your work.

[Update: Unbelievably, their second response is still the exact same automated reply, which ends like the first one with:

Si vous n'avez pas obtenu de réponse satisfaisante à votre question, répondez à cet email et un représentant de notre service clientèle vous contactera personnellement dès que possible.

If the response to your question was not satisfactory, respond to this email and a representative of our customer service will contact your personally as soon as possible.

Clearly fighting a system designed to get rid of me.

Very bad customer experience if you ask me.