On Fri, 29 Mar 2024 00:13:42 +0000, Mark Brown broonie@kernel.org wrote:
As part of the lazy FPSIMD state transitioning done by the hypervisor we currently share the userpsace FPSIMD state in thread->uw.fpsimd_state with the host. Since this struct is non-extensible userspace ABI we have to keep
Using the same representation is just pure convenience, and nothing requires us to use the it in the kernel/hypervisor.
the definition as is but the addition of FPMR in the 2023 dpISA means that we will want to share more storage with the host. To facilitate this refactor the current code to share the entire thread->uw rather than just the one field.
So this increase the required sharing with EL2 from 528 bytes to 560. Not a huge deal, but definitely moving in the wrong direction. Is there any plans to add more stuff to this structure that wouldn't be *directly* relevant to the hypervisor?
The large number of references to fpsimd_state make it very inconvenient to add an additional wrapper struct.
Signed-off-by: Mark Brown broonie@kernel.org
arch/arm64/include/asm/kvm_host.h | 3 ++- arch/arm64/include/asm/processor.h | 2 +- arch/arm64/kvm/fpsimd.c | 13 ++++++------- arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 4 ++-- 5 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 9e8a496fb284..8a251f0da900 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -27,6 +27,7 @@ #include <asm/fpsimd.h> #include <asm/kvm.h> #include <asm/kvm_asm.h> +#include <asm/processor.h> #include <asm/vncr_mapping.h> #define __KVM_HAVE_ARCH_INTC_INITIALIZED @@ -640,7 +641,7 @@ struct kvm_vcpu_arch { struct kvm_guest_debug_arch vcpu_debug_state; struct kvm_guest_debug_arch external_debug_state;
- struct user_fpsimd_state *host_fpsimd_state; /* hyp VA */
- struct thread_struct_uw *host_uw; /* hyp VA */ struct task_struct *parent_task;
Well, this is going away, and you know it.
M.