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KVM: arm64: Remove host FPSIMD saving for non-protected KVM

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[ Upstream commit 8eca7f6d51 ]

Now that the host eagerly saves its own FPSIMD/SVE/SME state,
non-protected KVM never needs to save the host FPSIMD/SVE/SME state,
and the code to do this is never used. Protected KVM still needs to
save/restore the host FPSIMD/SVE state to avoid leaking guest state to
the host (and to avoid revealing to the host whether the guest used
FPSIMD/SVE/SME), and that code needs to be retained.

Remove the unused code and data structures.

To avoid the need for a stub copy of kvm_hyp_save_fpsimd_host() in the
VHE hyp code, the nVHE/hVHE version is moved into the shared switch
header, where it is only invoked when KVM is in protected mode.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-3-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mark Rutland
2025-03-21 00:16:03 +00:00
committed by Greg Kroah-Hartman
parent 806d5c1e1d
commit 73f64c676a
4 changed files with 0 additions and 8 deletions
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arch/arm64/include/asm/kvm_host.h
-1
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@@ -535,7 +535,6 @@ 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 task_struct *parent_task;
struct {
arch/arm64/kvm/fpsimd.c
-2
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@@ -49,8 +49,6 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
if (ret)
return ret;
vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
/*
* We need to keep current's task_struct pinned until its data has been
* unshared with the hypervisor to make sure it is not re-used by the
arch/arm64/kvm/hyp/include/hyp/switch.h
-4
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@@ -321,10 +321,6 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
}
isb();
/* Write out the host state if it's in the registers */
if (vcpu->arch.fp_state == FP_STATE_HOST_OWNED)
__fpsimd_save_state(vcpu->arch.host_fpsimd_state);
/* Restore the guest state */
if (sve_guest)
__hyp_sve_restore_guest(vcpu);
arch/arm64/kvm/hyp/nvhe/hyp-main.c
-1
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@@ -41,7 +41,6 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.fp_state = host_vcpu->arch.fp_state;
hyp_vcpu->vcpu.arch.debug_ptr = kern_hyp_va(host_vcpu->arch.debug_ptr);
hyp_vcpu->vcpu.arch.host_fpsimd_state = host_vcpu->arch.host_fpsimd_state;
hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2;