SRU requests submitted: Artful: https://lists.ubuntu.com/archives/kernel-team/2017-October/087488.html Zesty: https://lists.ubuntu.com/archives/kernel-team/2017-October/087491.html
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1721070 Title: powerpc/64s: Add workaround for P9 vector CI load issuenext Status in The Ubuntu-power-systems project: In Progress Status in linux package in Ubuntu: In Progress Status in linux source package in Zesty: In Progress Status in linux source package in Artful: In Progress Bug description: == SRU Justification == POWER9 DD2.1 and earlier has an issue where some cache inhibited vector load will return bad data. The fix is two part, one firmware/microcode part triggers HMI interrupts when hitting such loads, the other part is commit 5080332c2c89 from linux-next which then emulates the instructions in Linux. The affected instructions are limited to lxvd2x, lxvw4x, lxvb16x and lxvh8x. Commit ccd3cd361341 is needed as a prereq for Artful. Commits a3d96f70c147 and ccd3cd361341 are needed as prereqs for Zesty. == Fixes == a3d96f70c147 ("powerpc/64s: Fix system reset vs general interrupt reentrancy") ccd3cd361341 ("powerpc/mce: Move 64-bit machine check code into mce.c") 5080332c2c89 ("powerpc/64s: Add workaround for P9 vector CI load issue") == Regression Potential == These commits are specific to powerpc. They required some back porting but have been tested by IBM. -- Problem Description -- When an instruction triggers the HMI, all threads in the core will be sent to the HMI handler, not just the one running the vector load. In general, these spurious HMIs are detected by the emulation code and we just return back to the running process. Unfortunately, if a spurious interrupt occurs on a vector load that's to normal memory we have no way to detect that it's spurious (unless we walk the page tables, which is very expensive). In this case we emulate the load but we need do so using a vector load itself to ensure 128bit atomicity is preserved. Some additional debugfs emulated instruction counters are added also. In order to solve this bug, we need to cherry pick the following patch https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=5080332c2c893118dbc18755f35c8b0131cf0fc4 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/1721070/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
