Public bug reported: [Impact] * TSC clocksource not available in nested guests
[Test Case] * Spin up a nested Xenial/Bionic guest and check for 'tsc' at /sys/devices/system/clocksource/clocksource0/available_clocksource [Regression Potential] * The regression potential is low. Upstream code still maintains this behaviour of skipping calibration on guests, and tsc code verifies if the frequency is known before registering the clocksource * Patches were verified against the above test case, and also tested with stress-ng in both nested and non-nested guest scenarios [Fix] * By applying the upstream commits [0] [1], we skip refined calibration and register TSC as a clocksource directly if its frequency is known (via MSR or CPUID) [0] For Xenial only - https://git.kernel.org/linus/47c95a46d0f [1] https://git.kernel.org/linus/e10f78050323 ** Affects: linux (Ubuntu) Importance: Undecided Status: Incomplete ** Affects: linux (Ubuntu Xenial) Importance: Medium Status: Confirmed ** Affects: linux (Ubuntu Bionic) Importance: Medium Status: Confirmed ** Tags: sts ** Also affects: linux (Ubuntu Bionic) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Xenial) Importance: Undecided Status: New ** Changed in: linux (Ubuntu Xenial) Status: New => Confirmed ** Changed in: linux (Ubuntu Bionic) Status: New => Confirmed ** Changed in: linux (Ubuntu Xenial) Importance: Undecided => Medium ** Changed in: linux (Ubuntu Bionic) Importance: Undecided => Medium ** Tags added: sts ** Description changed: [Impact] - * TSC clocksource not available in nested guests + * TSC clocksource not available in nested guests [Test Case] - * Spin up a nested Xenial/Bionic guest and check for 'tsc' at - /sys/devices/system/clocksource/clocksource0/available_clocksource + * Spin up a nested Xenial/Bionic guest and check for 'tsc' at + /sys/devices/system/clocksource/clocksource0/available_clocksource [Regression Potential] - * The regression potential is low. Upstream code still maintains this - behaviour of skipping calibration on guests, and tsc code verifies if - the frequency is known before registering the clocksource + * The regression potential is low. Upstream code still maintains this + behaviour of skipping calibration on guests, and tsc code verifies if + the frequency is known before registering the clocksource - * Patches were verified against the above test case, and also tested - with stress-ng in both nested and non-nested guest scenarios + * Patches were verified against the above test case, and also tested + with stress-ng in both nested and non-nested guest scenarios [Fix] - * By applying the upstream commits, we skip refined calibration and - register TSC as a clocksource directly if its frequency is known (via - MSR or CPUID) + * By applying the upstream commits [0] [1], we skip refined calibration and + register TSC as a clocksource directly if its frequency is known (via + MSR or CPUID) + + [0] For Xenial only - https://git.kernel.org/linus/47c95a46d0f + [1] https://git.kernel.org/linus/e10f78050323 -- 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/1822821 Title: TSC clocksource not available in nested guests Status in linux package in Ubuntu: Incomplete Status in linux source package in Xenial: Confirmed Status in linux source package in Bionic: Confirmed Bug description: [Impact] * TSC clocksource not available in nested guests [Test Case] * Spin up a nested Xenial/Bionic guest and check for 'tsc' at /sys/devices/system/clocksource/clocksource0/available_clocksource [Regression Potential] * The regression potential is low. Upstream code still maintains this behaviour of skipping calibration on guests, and tsc code verifies if the frequency is known before registering the clocksource * Patches were verified against the above test case, and also tested with stress-ng in both nested and non-nested guest scenarios [Fix] * By applying the upstream commits [0] [1], we skip refined calibration and register TSC as a clocksource directly if its frequency is known (via MSR or CPUID) [0] For Xenial only - https://git.kernel.org/linus/47c95a46d0f [1] https://git.kernel.org/linus/e10f78050323 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1822821/+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
