| Message ID | 20220528113829.1043361-1-maz@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM/arm64: Refactoring the vcpu flags | expand |
On 2022-05-28 12:38, Marc Zyngier wrote: [...] > This has been lightly tested on both VHE and nVHE systems, but not > with pKVM itself (there is a bit of work to rebase it on top of this > infrastructure). Patches on top of kvmarm-4.19 (there is a minor > conflict with Linus' current tree). As Will just pointed out to me in private, this should really read kvmarm-5.19, as that's what the patches are actually based on. I guess I'm still suffering from a form of Stockholm syndrome... M.
On Sat, 28 May 2022 12:38:10 +0100, Marc Zyngier wrote: > While working on pKVM, it slowly became apparent that dealing with the > flags was a pain, as they serve multiple purposes: > > - some flags are purely a configuration artefact, > > - some are an input from the host kernel to the world switch, > > [...] Applied to fixes, thanks! [01/18] KVM: arm64: Always start with clearing SVE flag on load commit: d52d165d67c5aa26c8c89909003c94a66492d23d [02/18] KVM: arm64: Always start with clearing SME flag on load commit: 039f49c4cafb785504c678f28664d088e0108d35 Cheers, M.
While working on pKVM, it slowly became apparent that dealing with the flags was a pain, as they serve multiple purposes: - some flags are purely a configuration artefact, - some are an input from the host kernel to the world switch, - a bunch of them are bookkeeping information for the kernel itself, - and finally some form a state machine between the host and the world switch. Given that, it became pretty hard to clearly delineate what needed to be conveyed between the host view of a vcpu and the shadow copy the world switch deals with, both on entry and exit. This has led to a flurry of bad bugs when developing the feature, and it is time to put some order in this mess. This series is roughly split in four parts: - patch 1 addresses an embarrassing bug that would leave SVE enabled for host EL0 once the vcpu had the flag set (it was never cleared), and patch 2 fix the same bug for SME, as it copied the bad behaviour (both patches are fix candidates for -rc1, and the first one carries a Cc stable). - patches 3 and 4 rid us of the FP flags altogether, as they really form a state machine that is better represented with an enum instead of dubious bit fiddling in both directions. - patch 5 through to 14 split all the flags into three distinct categories: configuration, input to the world switch, and host state, using some ugly^Wbeautiful^Wquestionable cpp tricks. - finally, the last patches add some cheap hardening and size optimisation to the new flags. With that in place, it should be much easier to reason about which flags need to be synchronised at runtime, and in which direction (for pKVM, this is only a subset of the input flags, and nothing else). This has been lightly tested on both VHE and nVHE systems, but not with pKVM itself (there is a bit of work to rebase it on top of this infrastructure). Patches on top of kvmarm-4.19 (there is a minor conflict with Linus' current tree). Marc Zyngier (18): KVM: arm64: Always start with clearing SVE flag on load KVM: arm64: Always start with clearing SME flag on load KVM: arm64: Drop FP_FOREIGN_STATE from the hypervisor code KVM: arm64: Move FP state ownership from flag to a tristate KVM: arm64: Add helpers to manipulate vcpu flags among a set KVM: arm64: Add three sets of flags to the vcpu state KVM: arm64: Move vcpu configuration flags into their own set KVM: arm64: Move vcpu PC/Exception flags to the input flag set KVM: arm64: Move vcpu debug/SPE/TRBE flags to the input flag set KVM: arm64: Move vcpu SVE/SME flags to the state flag set KVM: arm64: Move vcpu ON_UNSUPPORTED_CPU flag to the state flag set KVM: arm64: Move vcpu WFIT flag to the state flag set KVM: arm64: Kill unused vcpu flags field KVM: arm64: Convert vcpu sysregs_loaded_on_cpu to a state flag KVM: arm64: Warn when PENDING_EXCEPTION and INCREMENT_PC are set together KVM: arm64: Add build-time sanity checks for flags KVM: arm64: Reduce the size of the vcpu flag members KVM: arm64: Document why pause cannot be turned into a flag arch/arm64/include/asm/kvm_emulate.h | 3 +- arch/arm64/include/asm/kvm_host.h | 192 +++++++++++++++------ arch/arm64/kvm/arch_timer.c | 2 +- arch/arm64/kvm/arm.c | 6 +- arch/arm64/kvm/debug.c | 22 +-- arch/arm64/kvm/fpsimd.c | 36 ++-- arch/arm64/kvm/handle_exit.c | 2 +- arch/arm64/kvm/hyp/exception.c | 23 ++- arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 6 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 24 +-- arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 4 +- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 8 +- arch/arm64/kvm/hyp/nvhe/switch.c | 6 +- arch/arm64/kvm/hyp/nvhe/sys_regs.c | 7 +- arch/arm64/kvm/hyp/vhe/switch.c | 4 +- arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 4 +- arch/arm64/kvm/inject_fault.c | 30 ++-- arch/arm64/kvm/reset.c | 6 +- arch/arm64/kvm/sys_regs.c | 12 +- 19 files changed, 238 insertions(+), 159 deletions(-)