- 20 Jun, 2021 1 commit
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Suraj Jitindar Singh authored
The POWER9 vCPU TLB management code assumes all threads in a core share a TLB, and that TLBIEL execued by one thread will invalidate TLBs for all threads. This is not the case for SMT8 capable POWER9 and POWER10 (big core) processors, where the TLB is split between groups of threads. This results in TLB multi-hits, random data corruption, etc. Fix this by introducing cpu_first_tlb_thread_sibling etc., to determine which siblings share TLBs, and use that in the guest TLB flushing code. [npiggin@gmail.com: add changelog and comment] Signed-off-by:
Paul Mackerras <paulus@ozlabs.org> Signed-off-by:
Nicholas Piggin <npiggin@gmail.com> Reviewed-by:
Fabiano Rosas <farosas@linux.ibm.com> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210602040441.3984352-1-npiggin@gmail.com
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- 10 Jun, 2021 32 commits
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Nicholas Piggin authored
POWER9 and later processors always go via the P9 guest entry path now. Remove the remaining support from the P7/8 path. Signed-off-by:
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Nicholas Piggin authored
Implement support for hash guests under hash host. This has to save and restore the host SLB, and ensure that the MMU is off while switching into the guest SLB. POWER9 and later CPUs now always go via the P9 path. The "fast" guest mode is now renamed to the P9 mode, which is consistent with its functionality and the rest of the naming. Signed-off-by:
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Nicholas Piggin authored
Implement hash guest support. Guest entry/exit has to restore and save/clear the SLB, plus several other bits to accommodate hash guests in the P9 path. Radix host, hash guest support is removed from the P7/8 path. The HPT hcalls and faults are not handled in real mode, which is a performance regression. A worst-case fork/exit microbenchmark takes 3x longer after this patch. kbuild benchmark performance is in the noise, but the slowdown is likely to be noticed somewhere. For now, accept this penalty for the benefit of simplifying the P7/8 paths and unifying P9 hash with the new code, because hash is a less important configuration than radix on processors that support it. Hash will benefit from future optimisations to this path, including possibly a faster path to handle such hcalls and interrupts without doing a full exit. Signed-off-by:
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Nicholas Piggin authored
The reflection of sc 1 interrupts from guest PR=1 to the guest kernel is required to support a hash guest running PR KVM where its guest is making hcalls with sc 1. In preparation for hash guest support, add this hcall reflection to the P9 path. The P7/8 path does this in its realmode hcall handler (sc_1_fast_return). Signed-off-by:
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Nicholas Piggin authored
In order to support hash guests in the P9 path (which does not do real mode hcalls or page fault handling), these real-mode hash specific interrupts need to be implemented in virt mode. Signed-off-by:
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Nicholas Piggin authored
Functionality should not be changed. Signed-off-by:
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Nicholas Piggin authored
All radix guests go via the P9 path now, so there is no need to limit nested HV to processors that support "mixed mode" MMU. Remove the restriction. Signed-off-by:
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Nicholas Piggin authored
Commit f3c18e93 ("KVM: PPC: Book3S HV: Use XICS hypercalls when running as a nested hypervisor") added nested HV tests in XICS hypercalls, but not all are required. * icp_eoi is only called by kvmppc_deliver_irq_passthru which is only called by kvmppc_check_passthru which is only caled by kvmppc_read_one_intr. * kvmppc_read_one_intr is only called by kvmppc_read_intr which is only called by the L0 HV rmhandlers code. * kvmhv_rm_send_ipi is called by: - kvmhv_interrupt_vcore which is only called by kvmhv_commence_exit which is only called by the L0 HV rmhandlers code. - icp_send_hcore_msg which is only called by icp_rm_set_vcpu_irq. - icp_rm_set_vcpu_irq which is only called by icp_rm_try_update - icp_rm_set_vcpu_irq is not nested HV safe because it writes to LPCR directly without a kvmhv_on_pseries test. Nested handlers should not in general be using the rm handlers. The important test seems to be in kvmppc_ipi_thread, which sends the virt-mode H_IPI handler kick to use smp_call_function rather than msgsnd. Signed-off-by:
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Nicholas Piggin authored
Now that the P7/8 path no longer supports radix, real-mode handlers do not need to deal with being called in virt mode. This change effectively reverts commit acde2572 ("KVM: PPC: Book3S HV: Add radix checks in real-mode hypercall handlers"). It removes a few more real-mode tests in rm hcall handlers, which allows the indirect ops for the xive module to be removed from the built-in xics rm handlers. kvmppc_h_random is renamed to kvmppc_rm_h_random to be a bit more descriptive and consistent with other rm handlers. Signed-off-by:
Cédric Le Goater <clg@kaod.org> Signed-off-by:
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Nicholas Piggin authored
The P9 path now runs all supported radix guest combinations, so remove radix guest support from the P7/8 path. Signed-off-by:
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Nicholas Piggin authored
Dependent-threads mode is the normal KVM mode for pre-POWER9 SMT processors, where all threads in a core (or subcore) would run the same partition at the same time, or they would run the host. This design was mandated by MMU state that is shared between threads in a processor, so the synchronisation point is in hypervisor real-mode that has essentially no shared state, so it's safe for multiple threads to gather and switch to the correct mode. It is implemented by having the host unplug all secondary threads and always run in SMT1 mode, and host QEMU threads essentially represent virtual cores that wake these secondary threads out of unplug when the ioctl is called to run the guest. This happens via a side-path that is mostly invisible to the rest of the Linux host and the secondary threads still appear to be unplugged. POWER9 / ISA v3.0 has a more flexible MMU design that is independent per-thread and allows a much simpler KVM implementation. Before the new "P9 fast path" was added that began to take advantage of this, POWER9 support was implemented in the existing path which has support to run in the dependent threads mode. So it was not much work to add support to run POWER9 in this dependent threads mode. The mode is not required by the POWER9 MMU (although "mixed-mode" hash / radix MMU limitations of early processors were worked around using this mode). But it is one way to run SMT guests without running different guests or guest and host on different threads of the same core, so it could avoid or reduce some SMT attack surfaces without turning off SMT entirely. This security feature has some real, if indeterminate, value. However the old path is lagging in features (nested HV), and with this series the new P9 path adds remaining missing features (radix prefetch bug and hash support, in later patches), so POWER9 dependent threads mode support would be the only remaining reason to keep that code in and keep supporting POWER9/POWER10 in the old path. So here we make the call to drop this feature. Remove dependent threads mode support for POWER9 and above processors. Systems can still achieve this security by disabling SMT entirely, but that would generally come at a larger performance cost for guests. Signed-off-by:
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Nicholas Piggin authored
Rather than partition the guest PID space + flush a rogue guest PID to work around this problem, instead fix it by always disabling the MMU when switching in or out of guest MMU context in HV mode. This may be a bit less efficient, but it is a lot less complicated and allows the P9 path to trivally implement the workaround too. Newer CPUs are not subject to this issue. Signed-off-by:
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Nicholas Piggin authored
Move MMU context switch as late as reasonably possible to minimise code running with guest context switched in. This becomes more important when this code may run in real-mode, with later changes. Move WARN_ON as early as possible so program check interrupts are less likely to tangle everything up. Signed-off-by:
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Nicholas Piggin authored
This is a first step to wrapping supervisor and user SPR saving and loading up into helpers, which will then be called independently in bare metal and nested HV cases in order to optimise SPR access. Signed-off-by:
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Nicholas Piggin authored
This is wasted work if the time limit is exceeded. Signed-off-by:
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Nicholas Piggin authored
The C conversion caused exit timing to become a bit cramped. Expand it to cover more of the entry and exit code. Signed-off-by:
Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by:
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Nicholas Piggin authored
SRR0/1, DAR, DSISR must all be protected from machine check which can clobber them. Ensure MSR[RI] is clear while they are live. Signed-off-by:
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Nicholas Piggin authored
Now the initial C implementation is done, inline more HV code to make rearranging things easier. And rename __kvmhv_vcpu_entry_p9 to drop the leading underscores as it's now C, and is now a more complete vcpu entry. Signed-off-by:
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Nicholas Piggin authored
Almost all logic is moved to C, by introducing a new in_guest mode for the P9 path that branches very early in the KVM interrupt handler to P9 exit code. The main P9 entry and exit assembly is now only about 160 lines of low level stack setup and register save/restore, plus a bad-interrupt handler. There are two motivations for this, the first is just make the code more maintainable being in C. The second is to reduce the amount of code running in a special KVM mode, "realmode". In quotes because with radix it is no longer necessarily real-mode in the MMU, but it still has to be treated specially because it may be in real-mode, and has various important registers like PID, DEC, TB, etc set to guest. This is hostile to the rest of Linux and can't use arbitrary kernel functionality or be instrumented well. This initial patch is a reasonably faithful conversion of the asm code, but it does lack any loop to return quickly back into the guest without switching out of realmode in the case of unimportant or easily handled interrupts. As explained in previous changes, handling HV interrupts very quickly in this low level realmode is not so important for P9 performance, and are important to avoid for security, observability, debugability reasons. Signed-off-by:
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Nicholas Piggin authored
In the interest of minimising the amount of code that is run in "real-mode", don't handle hcalls in real mode in the P9 path. This requires some new handlers for H_CEDE and xics-on-xive to be added before xive is pulled or cede logic is checked. This introduces a change in radix guest behaviour where radix guests that execute 'sc 1' in userspace now get a privilege fault whereas previously the 'sc 1' would be reflected as a syscall interrupt to the guest kernel. That reflection is only required for hash guests that run PR KVM. Background: In POWER8 and earlier processors, it is very expensive to exit from the HV real mode context of a guest hypervisor interrupt, and switch to host virtual mode. On those processors, guest->HV interrupts reach the hypervisor with the MMU off because the MMU is loaded with guest context (LPCR, SDR1, SLB), and the other threads in the sub-core need to be pulled out of the guest too. Then the primary must save off guest state, invalidate SLB and ERAT, and load up host state before the MMU can be enabled to run in host virtual mode (~= regular Linux mode). Hash guests also require a lot of hcalls to run due to the nature of the MMU architecture and paravirtualisation design. The XICS interrupt controller requires hcalls to run. So KVM traditionally tries hard to avoid the full exit, by handling hcalls and other interrupts in real mode as much as possible. By contrast, POWER9 has independent MMU context per-thread, and in radix mode the hypervisor is in host virtual memory mode when the HV interrupt is taken. Radix guests do not require significant hcalls to manage their translations, and xive guests don't need hcalls to handle interrupts. So it's much less important for performance to handle hcalls in real mode on POWER9. One caveat is that the TCE hcalls are performance critical, real-mode variants introduced for POWER8 in order to achieve 10GbE performance. Real mode TCE hcalls were found to be less important on POWER9, which was able to drive 40GBe networking without them (using the virt mode hcalls) but performance is still important. These hcalls will benefit from subsequent guest entry/exit optimisation including possibly a faster "partial exit" that does not entirely switch to host context to handle the hcall. Signed-off-by:
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Nicholas Piggin authored
Switching the MMU from radix<->radix mode is tricky particularly as the MMU can remain enabled and requires a certain sequence of SPR updates. Move these together into their own functions. This also includes the radix TLB check / flush because it's tied in to MMU switching due to tlbiel getting LPID from LPIDR. Signed-off-by:
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Nicholas Piggin authored
Move the xive management up so the low level register switching can be pushed further down in a later patch. XIVE MMIO CI operations can run in higher level code with machine checks, tracing, etc., available. Signed-off-by:
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Nicholas Piggin authored
irq_work's use of the DEC SPR is racy with guest<->host switch and guest entry which flips the DEC interrupt to guest, which could lose a host work interrupt. This patch closes one race, and attempts to comment another class of races. Signed-off-by:
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Nicholas Piggin authored
LPCR[HDICE]=0 suppresses hypervisor decrementer exceptions on some processors, so it must be enabled before HDEC is set. Rather than set it in the host LPCR then setting HDEC, move the HDEC update to after the guest MMU context (including LPCR) is loaded. There shouldn't be much concern with delaying HDEC by some 10s or 100s of nanoseconds by setting it a bit later. Signed-off-by:
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Nicholas Piggin authored
This is more symmetric with kvmppc_xive_push_vcpu, and has the advantage that it runs with the MMU on. The extra test added to the asm will go away with a future change. Signed-off-by:
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Nicholas Piggin authored
This sets up the same calling convention from interrupt entry to KVM interrupt handler for system calls as exists for other interrupt types. This is a better API, it uses a save area rather than SPR, and it has more registers free to use. Using a single common API helps maintain it, and it becomes easier to use in C in a later patch. Signed-off-by:
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Nicholas Piggin authored
The bad_host_intr check will never be true with PR KVM, move it to HV code. Signed-off-by:
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Nicholas Piggin authored
Like the earlier patch for hcalls, KVM interrupt entry requires a different calling convention than the Linux interrupt handlers set up. Move the code that converts from one to the other into KVM. Signed-off-by:
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Nicholas Piggin authored
System calls / hcalls have a different calling convention than other interrupts, so there is code in the KVMTEST to massage these into the same form as other interrupt handlers. Move this work into the KVM hcall handler. This means teaching KVM a little more about the low level interrupt handler setup, PACA save areas, etc., although that's not obviously worse than the current approach of coming up with an entirely different interrupt register / save convention. Signed-off-by:
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Nicholas Piggin authored
Add a separate hcall entry point. This can be used to deal with the different calling convention. Signed-off-by:
Daniel Axtens <dja@axtens.net> Reviewed-by:
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Nicholas Piggin authored
Move the GUEST_MODE_SKIP logic into KVM code. This is quite a KVM internal detail that has no real need to be in common handlers. Add a comment explaining the what and why of KVM "skip" interrupts. Signed-off-by:
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Nicholas Piggin authored
Rather than bifurcate the call depending on whether or not HV is possible, and have the HV entry test for PR, just make a single common point which does the demultiplexing. This makes it simpler to add another type of exit handler. Signed-off-by:
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- 04 Jun, 2021 1 commit
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Nicholas Piggin authored
Similar to commit 25edcc50 ("KVM: PPC: Book3S HV: Save and restore FSCR in the P9 path"), ensure the P7/8 path saves and restores the host FSCR. The logic explained in that patch actually applies there to the old path well: a context switch can be made before kvmppc_vcpu_run_hv restores the host FSCR and returns. Now both the p9 and the p7/8 paths now save and restore their FSCR, it no longer needs to be restored at the end of kvmppc_vcpu_run_hv Fixes: b005255e ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs") Cc: stable@vger.kernel.org # v3.14+ Signed-off-by:
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- 16 May, 2021 6 commits
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Linus Torvalds authored
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Linus Torvalds authored
Merge tag 'driver-core-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core fixes from Greg KH: "Here are two driver fixes for driver core changes that happened in 5.13-rc1. The clk driver fix resolves a many-reported issue with booting some devices, and the USB typec fix resolves the reported problem of USB systems on some embedded boards. Both of these have been in linux-next this week with no reported issues" * tag 'driver-core-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: clk: Skip clk provider registration when np is NULL usb: typec: tcpm: Don't block probing of consumers of "connector" nodes
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/stagingLinus Torvalds authored
Pull staging and IIO driver fixes from Greg KH: "Here are some small IIO driver fixes and one Staging driver fix for 5.13-rc2. Nothing major, just some resolutions for reported problems: - gcc-11 bogus warning fix for rtl8723bs - iio driver tiny fixes All of these have been in linux-next for many days with no reported issues" * tag 'staging-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: iio: tsl2583: Fix division by a zero lux_val iio: core: return ENODEV if ioctl is unknown iio: core: fix ioctl handlers removal iio: gyro: mpu3050: Fix reported temperature value iio: hid-sensors: select IIO_TRIGGERED_BUFFER under HID_SENSOR_IIO_TRIGGER iio: proximity: pulsedlight: Fix rumtime PM imbalance on error iio: light: gp2ap002: Fix rumtime PM imbalance on error staging: rtl8723bs: avoid bogus gcc warning
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usbLinus Torvalds authored
Pull USB fixes from Greg KH: "Here are some small USB fixes for 5.13-rc2. They consist of a number of resolutions for reported issues: - typec fixes for found problems - xhci fixes and quirk additions - dwc3 driver fixes - minor fixes found by Coverity - cdc-wdm fixes for reported problems All of these have been in linux-next for a few days with no reported issues" * tag 'usb-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (28 commits) usb: core: hub: fix race condition about TRSMRCY of resume usb: typec: tcpm: Fix SINK_DISCOVERY current limit for Rp-default xhci: Add reset resume quirk for AMD xhci controller. usb: xhci: Increase timeout for HC halt xhci: Do not use GFP_KERNEL in (potentially) atomic context xhci: Fix giving back cancelled URBs even if halted endpoint can't reset xhci-pci: Allow host runtime PM as default for Intel Alder Lake xHCI usb: musb: Fix an error message usb: typec: tcpm: Fix wrong handling for Not_Supported in VDM AMS usb: typec: tcpm: Send DISCOVER_IDENTITY from dedicated work usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4 usb: fotg210-hcd: Fix an error message docs: usb: function: Modify path name usb: dwc3: omap: improve extcon initialization usb: typec: ucsi: Put fwnode in any case during ->probe() usb: typec: tcpm: Fix wrong handling in GET_SINK_CAP usb: dwc2: Remove obsolete MODULE_ constants from platform.c usb: dwc3: imx8mp: fix error return code in dwc3_imx8mp_probe() usb: dwc3: imx8mp: detect dwc3 core node via compatible string usb: dwc3: gadget: Return success always for kick transfer in ep queue ...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull timer fixes from Thomas Gleixner: "Two fixes for timers: - Use the ALARM feature check in the alarmtimer core code insted of the old method of checking for the set_alarm() callback. Drivers can have that callback set but the feature bit cleared. If such a RTC device is selected then alarms wont work. - Use a proper define to let the preprocessor check whether Hyper-V VDSO clocksource should be active. The code used a constant in an enum with #ifdef, which evaluates to always false and disabled the clocksource for VDSO" * tag 'timers-urgent-2021-05-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: clocksource/drivers/hyper-v: Re-enable VDSO_CLOCKMODE_HVCLOCK on X86 alarmtimer: Check RTC features instead of ops -
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tipLinus Torvalds authored
Pull xen fixes from Juergen Gross: - two patches for error path fixes - a small series for fixing a regression with swiotlb with Xen on Arm * tag 'for-linus-5.13b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/swiotlb: check if the swiotlb has already been initialized arm64: do not set SWIOTLB_NO_FORCE when swiotlb is required xen/arm: move xen_swiotlb_detect to arm/swiotlb-xen.h xen/unpopulated-alloc: fix error return code in fill_list() xen/gntdev: fix gntdev_mmap() error exit path
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