kernel/arch/arm/include/asm/kvm_asm.h, branch linux-4.15.y

KVM: arm/arm64: Move timer save/restore out of the hyp code

2017-11-06T15:23:13Z

As we are about to be lazy with saving and restoring the timer registers, we prepare by moving all possible timer configuration logic out of the hyp code. All virtual timer registers can be programmed from EL1 and since the arch timer is always a level triggered interrupt we can safely do this with interrupts disabled in the host kernel on the way to the guest without taking vtimer interrupts in the host kernel (yet). The downside is that the cntvoff register can only be programmed from hyp mode, so we jump into hyp mode and back to program it. This is also safe, because the host kernel doesn't use the virtual timer in the KVM code. It may add a little performance performance penalty, but only until following commits where we move this operation to vcpu load/put. Signed-off-by: Christoffer Dall Reviewed-by: Marc Zyngier

ARM: KVM: Gracefully handle hyp-stubs being restored from under our feet

2017-04-09T14:49:31Z

Should kvm_reboot() be invoked while guest is running, an IPI wil be issued, forcing the guest to exit and HYP being reset to the stubs. We will then try to reenter the guest, only to get an error (HVC_STUB_ERR). This patch allows this case to be gracefully handled by exiting the run loop. Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall

ARM: KVM: Convert __cpu_reset_hyp_mode to using __hyp_reset_vectors

2017-04-09T14:49:30Z

We are now able to use the hyp stub to reset HYP mode. Time to kiss __kvm_hyp_reset goodbye, and use __hyp_reset_vectors. Tested-by: Keerthy Acked-by: Russell King Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall

KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put

2017-04-09T14:45:22Z

We don't have to save/restore the VMCR on every entry to/from the guest, since on GICv2 we can access the control interface from EL1 and on VHE systems with GICv3 we can access the control interface from KVM running in EL2. GICv3 systems without VHE becomes the rare case, which has to save/restore the register on each round trip. Note that userspace accesses may see out-of-date values if the VCPU is running while accessing the VGIC state via the KVM device API, but this is already the case and it is up to userspace to quiesce the CPUs before reading the CPU registers from the GIC for an up-to-date view. Reviewed-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Christoffer Dall

arm/arm64: KVM: Perform local TLB invalidation when multiplexing vcpus on a single CPU

2016-11-04T17:56:28Z

Architecturally, TLBs are private to the (physical) CPU they're associated with. But when multiple vcpus from the same VM are being multiplexed on the same CPU, the TLBs are not private to the vcpus (and are actually shared across the VMID). Let's consider the following scenario: - vcpu-0 maps PA to VA - vcpu-1 maps PA' to VA If run on the same physical CPU, vcpu-1 can hit TLB entries generated by vcpu-0 accesses, and access the wrong physical page. The solution to this is to keep a per-VM map of which vcpu ran last on each given physical CPU, and invalidate local TLBs when switching to a different vcpu from the same VM. Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier

ARM: KVM: Support vgic-v3

2016-09-22T11:22:21Z

This patch allows to build and use vgic-v3 in 32-bit mode. Unfortunately, it can not be split in several steps without extra stubs to keep patches independent and bisectable. For instance, virt/kvm/arm/vgic/vgic-v3.c uses function from vgic-v3-sr.c, handling access to GICv3 cpu interface from the guest requires vgic_v3.vgic_sre to be already defined. It is how support has been done: * handle SGI requests from the guest * report configured SRE on access to GICv3 cpu interface from the guest * required vgic-v3 macros are provided via uapi.h * static keys are used to select GIC backend * to make vgic-v3 build KVM_ARM_VGIC_V3 guard is removed along with the static inlines Acked-by: Marc Zyngier Reviewed-by: Christoffer Dall Signed-off-by: Vladimir Murzin Signed-off-by: Christoffer Dall

arm: KVM: Allow an exit code to be tagged with a Virtual Abort

2016-09-08T10:53:00Z

An asynchronous abort can also be triggered whilst running at EL2. But instead of making that a new error code, we need to communicate it to the rest of KVM together with the exit reason. So let's hijack a single bit that allows the exception code to be tagged with a "pending Abort" information. Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall

arm: KVM: Allow hyp teardown

2016-07-03T21:41:27Z

So far, KVM was getting in the way of kexec on 32bit (and the arm64 kexec hackers couldn't be bothered to fix it on 32bit...). With simpler page tables, tearing KVM down becomes very easy, so let's just do it. Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-03-18T03:03:47Z

Pull arm64 updates from Catalin Marinas: "Here are the main arm64 updates for 4.6. There are some relatively intrusive changes to support KASLR, the reworking of the kernel virtual memory layout and initial page table creation. Summary: - Initial page table creation reworked to avoid breaking large block mappings (huge pages) into smaller ones. The ARM architecture requires break-before-make in such cases to avoid TLB conflicts but that's not always possible on live page tables - Kernel virtual memory layout: the kernel image is no longer linked to the bottom of the linear mapping (PAGE_OFFSET) but at the bottom of the vmalloc space, allowing the kernel to be loaded (nearly) anywhere in physical RAM - Kernel ASLR: position independent kernel Image and modules being randomly mapped in the vmalloc space with the randomness is provided by UEFI (efi_get_random_bytes() patches merged via the arm64 tree, acked by Matt Fleming) - Implement relative exception tables for arm64, required by KASLR (initial code for ARCH_HAS_RELATIVE_EXTABLE added to lib/extable.c but actual x86 conversion to deferred to 4.7 because of the merge dependencies) - Support for the User Access Override feature of ARMv8.2: this allows uaccess functions (get_user etc.) to be implemented using LDTR/STTR instructions. Such instructions, when run by the kernel, perform unprivileged accesses adding an extra level of protection. The set_fs() macro is used to "upgrade" such instruction to privileged accesses via the UAO bit - Half-precision floating point support (part of ARMv8.2) - Optimisations for CPUs with or without a hardware prefetcher (using run-time code patching) - copy_page performance improvement to deal with 128 bytes at a time - Sanity checks on the CPU capabilities (via CPUID) to prevent incompatible secondary CPUs from being brought up (e.g. weird big.LITTLE configurations) - valid_user_regs() reworked for better sanity check of the sigcontext information (restored pstate information) - ACPI parking protocol implementation - CONFIG_DEBUG_RODATA enabled by default - VDSO code marked as read-only - DEBUG_PAGEALLOC support - ARCH_HAS_UBSAN_SANITIZE_ALL enabled - Erratum workaround Cavium ThunderX SoC - set_pte_at() fix for PROT_NONE mappings - Code clean-ups" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (99 commits) arm64: kasan: Fix zero shadow mapping overriding kernel image shadow arm64: kasan: Use actual memory node when populating the kernel image shadow arm64: Update PTE_RDONLY in set_pte_at() for PROT_NONE permission arm64: Fix misspellings in comments. arm64: efi: add missing frame pointer assignment arm64: make mrs_s prefixing implicit in read_cpuid arm64: enable CONFIG_DEBUG_RODATA by default arm64: Rework valid_user_regs arm64: mm: check at build time that PAGE_OFFSET divides the VA space evenly arm64: KVM: Move kvm_call_hyp back to its original localtion arm64: mm: treat memstart_addr as a signed quantity arm64: mm: list kernel sections in order arm64: lse: deal with clobbered IP registers after branch via PLT arm64: mm: dump: Use VA_START directly instead of private LOWEST_ADDR arm64: kconfig: add submenu for 8.2 architectural features arm64: kernel: acpi: fix ioremap in ACPI parking protocol cpu_postboot arm64: Add support for Half precision floating point arm64: Remove fixmap include fragility arm64: Add workaround for Cavium erratum 27456 arm64: mm: Mark .rodata as RO ...

ARM: KVM: Remove __kvm_hyp_exit/__kvm_hyp_exit_end

2016-02-29T18:34:15Z

I have no idea what these were for - probably a leftover from an early implementation. Good bye! Acked-by: Christoffer Dall Signed-off-by: Marc Zyngier