| Message ID | 20230916003118.2540661-1-seanjc@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: vfio: Hide KVM internals from others | expand |
> -----Original Message----- > From: Sean Christopherson <seanjc@google.com> > Sent: Saturday, September 16, 2023 1:31 AM > To: Catalin Marinas <catalin.marinas@arm.com>; Will Deacon > <will@kernel.org>; Marc Zyngier <maz@kernel.org>; Oliver Upton > <oliver.upton@linux.dev>; Huacai Chen <chenhuacai@kernel.org>; Michael > Ellerman <mpe@ellerman.id.au>; Anup Patel <anup@brainfault.org>; Paul > Walmsley <paul.walmsley@sifive.com>; Palmer Dabbelt > <palmer@dabbelt.com>; Albert Ou <aou@eecs.berkeley.edu>; Heiko > Carstens <hca@linux.ibm.com>; Vasily Gorbik <gor@linux.ibm.com>; > Alexander Gordeev <agordeev@linux.ibm.com>; Christian Borntraeger > <borntraeger@linux.ibm.com>; Janosch Frank <frankja@linux.ibm.com>; > Claudio Imbrenda <imbrenda@linux.ibm.com>; Thomas Gleixner > <tglx@linutronix.de>; Ingo Molnar <mingo@redhat.com>; Borislav Petkov > <bp@alien8.de>; Dave Hansen <dave.hansen@linux.intel.com>; > x86@kernel.org; Peter Zijlstra <peterz@infradead.org>; Arnaldo Carvalho de > Melo <acme@kernel.org>; Sean Christopherson <seanjc@google.com>; > Paolo Bonzini <pbonzini@redhat.com>; Tony Krowiak > <akrowiak@linux.ibm.com>; Halil Pasic <pasic@linux.ibm.com>; Jason Herne > <jjherne@linux.ibm.com>; Harald Freudenberger <freude@linux.ibm.com>; > Alex Williamson <alex.williamson@redhat.com>; Andy Lutomirski > <luto@kernel.org> > Cc: linux-arm-kernel@lists.infradead.org; kvmarm@lists.linux.dev; linux- > mips@vger.kernel.org; kvm@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; > kvm-riscv@lists.infradead.org; linux-riscv@lists.infradead.org; linux- > s390@vger.kernel.org; linux-kernel@vger.kernel.org; linux-perf- > users@vger.kernel.org; Anish Ghulati <aghulati@google.com>; Venkatesh > Srinivas <venkateshs@chromium.org>; Andrew Thornton > <andrewth@google.com> > Subject: [PATCH 00/26] KVM: vfio: Hide KVM internals from others > > This is a borderline RFC series to hide KVM's internals from the rest of > the kernel, where "internals" means data structures, enums, #defines, > APIs, etc. that are intended to be KVM-only, but are exposed everywhere > due to kvm_host.h (and other headers) living in the global include paths. > > The motiviation for hiding KVM's internals is to allow *safely* loading a > "new" KVM module without having to reboot the host. Where "new" doesn't > have to be strictly newer, just a different incarnation of KVM. Hiding > KVM's internals means those assets can change across KVM instances > without > breaking things, e.g. would allow modifying the layout of struct kvm_vcpu > to introduce new fields related to a new feature or mitigation for hardware > bugs. > > The end goal for all of this is to allow loading and running multiple > instances of KVM (the module) simultaneously on a single host, e.g. to > deploy fixes, mitigations, and/or new features without having to drain > all VMs from the host. > > For now, the immediate goal is to get KVM to a state where KVM x86 doesn't > expose anything to the broader world that isn't intended for external > consumption, e.g. the page write-tracking APIs used by KVM-GT. > > I say this is borderline RFC because I don't think I've "formally" proposed > the idea of hiding KVM internals before now. I decided not to tag this RFC > because the changes ended up being not _that_ invasive, and everything > before the last six patches is worthwhile even if hiding internals is > ultimately rejected (IMO). > > This would ideally be ~5 separate series, and I certainly have no objection > if that's how we want to get this stuff merged. E.g. (1) VFIO cleanups, > (2) drop HAVE_KVM, (3) clean up makefiles, (4) x86 perf cleanup, and > (5) final push for hiding state. The HAVE_KVM and virt/kvm include stuff > isn't strictly necessary, but I included them here because they're > relatively minor (in the grand scheme). Hi Sean, Just thought of checking with you on this series. Do you have plans to revive this series? The reason I am asking is, on ARM64/KVM side we do have a requirement to share the KVM VMID with SMMUV3. Please see the RFC I sent out earlier this year[1]. The series basically provides a way for KVM to pin a VMID and also associates an iommufd ctx with a struct kvm * to retrieve that VMID. As mentioned above, some of the patches in this series(especially 1-4 & 6) that does the VFIO cleanups and dropping CONFIG_KVM_VFIO looks very straightforward and useful. I am thinking of including those when I re-spin my RFC series, if that’s ok. Please let me know your thoughts. Thanks, Shameer [1]. https://lore.kernel.org/linux-iommu/20240209115824.GA2922446@myrica/
This is a borderline RFC series to hide KVM's internals from the rest of the kernel, where "internals" means data structures, enums, #defines, APIs, etc. that are intended to be KVM-only, but are exposed everywhere due to kvm_host.h (and other headers) living in the global include paths. The motiviation for hiding KVM's internals is to allow *safely* loading a "new" KVM module without having to reboot the host. Where "new" doesn't have to be strictly newer, just a different incarnation of KVM. Hiding KVM's internals means those assets can change across KVM instances without breaking things, e.g. would allow modifying the layout of struct kvm_vcpu to introduce new fields related to a new feature or mitigation for hardware bugs. The end goal for all of this is to allow loading and running multiple instances of KVM (the module) simultaneously on a single host, e.g. to deploy fixes, mitigations, and/or new features without having to drain all VMs from the host. For now, the immediate goal is to get KVM to a state where KVM x86 doesn't expose anything to the broader world that isn't intended for external consumption, e.g. the page write-tracking APIs used by KVM-GT. I say this is borderline RFC because I don't think I've "formally" proposed the idea of hiding KVM internals before now. I decided not to tag this RFC because the changes ended up being not _that_ invasive, and everything before the last six patches is worthwhile even if hiding internals is ultimately rejected (IMO). This would ideally be ~5 separate series, and I certainly have no objection if that's how we want to get this stuff merged. E.g. (1) VFIO cleanups, (2) drop HAVE_KVM, (3) clean up makefiles, (4) x86 perf cleanup, and (5) final push for hiding state. The HAVE_KVM and virt/kvm include stuff isn't strictly necessary, but I included them here because they're relatively minor (in the grand scheme). We've explore several alternatives to the #ifdef __KVM__ approach, and they all sucked, hard. What I really wanted (and still want) to do, is to bury the bulk of kvm_host.h (and other KVM headers) in virt/kvm, but every attempt to do that ended in flames. Even with the __KVM__ guards in place, each architecture's kvm_host.h is too intertwined with the common kvm_host.h, and trying to extract small-ish pieces just doesn't work (each patch inevitably snowballed into a gigantic beast). The other idea we considered (which I thought of, and feel dirty for even proposing it internally), is to move all headers under virt/kvm, add virt/kvm/include to the global header path, and then have KVM x86 omit virt/kvm/include when configured to hide KVM internals. I hate this idea because it sets a bad precedent, and requires a lot of file movement without providing any benefit to other architectures. E.g. I hope that guarding KVM internals with #ifdef __KVM__ will allow us to slowly clean things up so that some day KVM only exposes a handful of APIs to the rest of the kernel (probably a pipe dream). Anish Ghulati (1): KVM: arm64: Move arm_{psci,hypercalls}.h to an internal KVM path Sean Christopherson (25): vfio: Wrap KVM helpers with CONFIG_KVM instead of CONFIG_HAVE_KVM vfio: Move KVM get/put helpers to colocate it with other KVM related code virt: Declare and define vfio_file_set_kvm() iff CONFIG_KVM is enabled vfio: Add struct to hold KVM assets and dedup group vs. iommufd code vfio: KVM: Pass get/put helpers from KVM to VFIO, don't do circular lookup KVM: Drop CONFIG_KVM_VFIO and just look at KVM+VFIO x86/idt: Wrap KVM logic with CONFIG_KVM instead of CONFIG_HAVE_KVM KVM: x86: Stop selecting and depending on HAVE_KVM KVM: arm64: Stop selecting and depending on HAVE_KVM KVM: s390: Stop selecting and depending on HAVE_KVM KVM: MIPS: Make HAVE_KVM a MIPS-only Kconfig KVM: arm64: Include KVM headers to get forward declarations KVM: arm64: Move ARM specific headers in include/kvm to arch directory KVM: Move include/kvm/iodev.h to include/linux as kvm_iodev.h KVM: MIPS: Stop adding virt/kvm to the arch include path KVM: PPC: Stop adding virt/kvm to the arch include path KVM: s390: Stop adding virt/kvm to the arch include path KVM: Standardize include paths across all architectures perf/x86: KVM: Have perf define a dedicated struct for getting guest PEBS data entry/kvm: Drop @vcpu param from arch_xfer_to_guest_mode_handle_work() entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper KVM: arm64: Move and consolidate "public" functions in asm/kvm_host.h powerpc/xics: Move declaration of xics_wake_cpu() out of kvm_ppc.h KVM: PPC: Rearrange code in kvm_ppc.h to isolate "public" information KVM: Hide KVM internal data structures and values from kernel at-large MAINTAINERS | 1 - arch/arm64/Kconfig | 1 - .../arm64/include/asm/kvm_arch_timer.h | 2 + arch/arm64/include/asm/kvm_emulate.h | 3 + arch/arm64/include/asm/kvm_host.h | 57 ++-- arch/arm64/include/asm/kvm_mmu.h | 4 + .../arm64/include/asm/kvm_pmu.h | 2 + .../arm64/include/asm/kvm_vgic.h | 2 +- arch/arm64/kernel/asm-offsets.c | 2 + arch/arm64/kvm/Kconfig | 2 - arch/arm64/kvm/Makefile | 2 - arch/arm64/kvm/arch_timer.c | 5 +- arch/arm64/kvm/arm.c | 9 +- {include => arch/arm64}/kvm/arm_hypercalls.h | 0 {include => arch/arm64}/kvm/arm_psci.h | 0 arch/arm64/kvm/guest.c | 2 +- arch/arm64/kvm/handle_exit.c | 2 +- arch/arm64/kvm/hyp/Makefile | 4 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 4 +- arch/arm64/kvm/hyp/nvhe/Makefile | 3 +- arch/arm64/kvm/hyp/nvhe/switch.c | 4 +- arch/arm64/kvm/hyp/vhe/Makefile | 2 +- arch/arm64/kvm/hyp/vhe/switch.c | 4 +- arch/arm64/kvm/hypercalls.c | 4 +- arch/arm64/kvm/pmu-emul.c | 6 +- arch/arm64/kvm/psci.c | 4 +- arch/arm64/kvm/pvtime.c | 2 +- arch/arm64/kvm/reset.c | 3 +- arch/arm64/kvm/trace_arm.h | 2 +- arch/arm64/kvm/trng.c | 2 +- arch/arm64/kvm/vgic/vgic-debug.c | 2 +- arch/arm64/kvm/vgic/vgic-init.c | 2 +- arch/arm64/kvm/vgic/vgic-irqfd.c | 2 +- arch/arm64/kvm/vgic/vgic-kvm-device.c | 2 +- arch/arm64/kvm/vgic/vgic-mmio-v2.c | 4 +- arch/arm64/kvm/vgic/vgic-mmio-v3.c | 4 +- arch/arm64/kvm/vgic/vgic-mmio.c | 6 +- arch/arm64/kvm/vgic/vgic-v2.c | 2 +- arch/arm64/kvm/vgic/vgic-v3.c | 2 +- arch/mips/include/asm/kvm_host.h | 5 +- arch/mips/kernel/asm-offsets.c | 2 + arch/mips/kvm/Kconfig | 3 + arch/mips/kvm/Makefile | 2 - arch/powerpc/include/asm/kvm_book3s.h | 3 + arch/powerpc/include/asm/kvm_book3s_64.h | 2 + arch/powerpc/include/asm/kvm_booke.h | 4 + arch/powerpc/include/asm/kvm_host.h | 7 +- arch/powerpc/include/asm/kvm_ppc.h | 306 +++++++++--------- arch/powerpc/include/asm/xics.h | 3 + arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kvm/Kconfig | 1 - arch/powerpc/kvm/Makefile | 2 - arch/powerpc/kvm/mpic.c | 2 +- arch/riscv/include/asm/kvm_host.h | 3 + arch/riscv/kernel/asm-offsets.c | 1 + arch/riscv/kvm/Makefile | 2 - arch/riscv/kvm/aia_aplic.c | 2 +- arch/riscv/kvm/aia_imsic.c | 2 +- arch/riscv/kvm/vcpu.c | 2 +- arch/s390/Kconfig | 1 - arch/s390/include/asm/kvm_host.h | 7 +- arch/s390/kernel/asm-offsets.c | 1 + arch/s390/kvm/Kconfig | 2 - arch/s390/kvm/Makefile | 2 - arch/x86/Kconfig | 1 - arch/x86/events/core.c | 5 +- arch/x86/events/intel/core.c | 18 +- arch/x86/events/perf_event.h | 3 +- arch/x86/include/asm/hardirq.h | 2 +- arch/x86/include/asm/idtentry.h | 2 +- arch/x86/include/asm/irq.h | 2 +- arch/x86/include/asm/irq_vectors.h | 2 +- arch/x86/include/asm/kvm_host.h | 12 +- arch/x86/include/asm/perf_event.h | 12 +- arch/x86/kernel/idt.c | 2 +- arch/x86/kernel/irq.c | 4 +- arch/x86/kvm/Kconfig | 3 - arch/x86/kvm/Makefile | 1 - arch/x86/kvm/i8254.h | 2 +- arch/x86/kvm/ioapic.h | 2 +- arch/x86/kvm/irq.h | 2 +- arch/x86/kvm/lapic.h | 2 +- arch/x86/kvm/vmx/pmu_intel.c | 16 +- arch/x86/kvm/vmx/vmx.c | 11 +- arch/x86/kvm/vmx/vmx.h | 2 +- arch/x86/kvm/x86.c | 3 +- drivers/s390/crypto/vfio_ap_drv.c | 1 + drivers/s390/crypto/vfio_ap_ops.c | 2 + drivers/vfio/device_cdev.c | 9 +- drivers/vfio/group.c | 18 +- drivers/vfio/vfio.h | 26 +- drivers/vfio/vfio_main.c | 139 ++++---- include/linux/entry-kvm.h | 10 +- include/linux/kvm_host.h | 17 +- include/{kvm/iodev.h => linux/kvm_iodev.h} | 0 include/linux/kvm_types.h | 3 + include/linux/vfio.h | 6 +- include/trace/events/kvm.h | 5 + kernel/entry/kvm.c | 13 +- scripts/gdb/linux/constants.py.in | 2 +- scripts/gdb/linux/interrupts.py | 2 +- tools/arch/x86/include/asm/irq_vectors.h | 2 +- virt/kvm/Kconfig | 6 - virt/kvm/Makefile.kvm | 6 +- virt/kvm/coalesced_mmio.c | 3 +- virt/kvm/eventfd.c | 2 +- virt/kvm/kvm_main.c | 3 +- virt/kvm/vfio.c | 9 +- virt/kvm/vfio.h | 2 +- 109 files changed, 489 insertions(+), 440 deletions(-) rename include/kvm/arm_arch_timer.h => arch/arm64/include/asm/kvm_arch_timer.h (98%) rename include/kvm/arm_pmu.h => arch/arm64/include/asm/kvm_pmu.h (99%) rename include/kvm/arm_vgic.h => arch/arm64/include/asm/kvm_vgic.h (99%) rename {include => arch/arm64}/kvm/arm_hypercalls.h (100%) rename {include => arch/arm64}/kvm/arm_psci.h (100%) rename include/{kvm/iodev.h => linux/kvm_iodev.h} (100%) base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d