On Thu, Apr 4, 2013 at 11:51 AM, Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: > Oh, you want the bug report that I'm fixing this against? Sure, I can do that. > I thought you wanted me to include a url in the WARN_TAINT, with which user > could report occurances of this bug. Yeah, the bug that this is reported in is: > https://bugzilla.redhat.com/show_bug.cgi?id=887006 > > Its standing in for about a dozen or so variants of this issue we've seen Exactly -- I'm just hoping for something in the changelog. BTW, this particular bugzilla is not public. > Regardless, theres also the security issue to consider here - namely that > disabling irq remapping opens up users of virt to a possible security bug > (potential irq injection). Some users may wish to live with the remapping > error, given that error typically leads to devices that need to be > restarted/reset to start working again, rather than live with the security hole. > I rather like the warning, that gives users a choice, but I'll spin up a version > that just disables it if you would rather. I don't believe users will want to make a choice like that or even be sophisticated enough to do it, at least not based on something in dmesg. I'm pretty sure I'm not :) The only supportable thing I can imagine doing would be: - Disable interrupt remapping if this chipset defect is present, so devices work reliably (they don't need whatever restart/reset you referred to above). - Disable virt functionality when interrupt remapping is disabled to avoid the security problem (I don't know the details of this.) - Add a command-line option to enable interrupt remapping (I think "intremap=on" is currently parsed too early, but maybe this could be reworked so the option could override the quirk disable). - Add release notes saying "boot with 'intremap=on' if you want the virt functionality and can accept unreliable devices." That way the default behavior is safe and reliable (though perhaps lacking some functionality), and you have told the user a way to get safe and unreliable operation if he's willing to accept that. At least, that's what I think I would want if I were in RH's shoes. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
