KVM: arm64: Do not map the host fpsimd state to hyp in pKVM

pKVM maintains its own state at EL2 for tracking the host fpsimd
state. Therefore, no need to map and share the host's view with
it.

Signed-off-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-12-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 4609d1b9dddede6355c910238e621ae30fb7a408..74dc5a60f17185ee2e7ca1084d903171f19398ea 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -663,8 +663,6 @@ struct kvm_vcpu_arch {
        struct kvm_guest_debug_arch vcpu_debug_state;
        struct kvm_guest_debug_arch external_debug_state;
 
-       struct task_struct *parent_task;
-
        /* VGIC state */
        struct vgic_cpu vgic_cpu;
        struct arch_timer_cpu timer_cpu;
@@ -1262,7 +1260,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu);
-void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu);
 
 static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr)
 {

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index d5837d65e4a1b6566a3834a3899d9714e064d534..63a6f82934a68d8bb393d0f74b649b31a846abb3 100644 (file)
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -14,19 +14,6 @@
 #include <asm/kvm_mmu.h>
 #include <asm/sysreg.h>
 
-void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu)
-{
-       struct task_struct *p = vcpu->arch.parent_task;
-       struct user_fpsimd_state *fpsimd;
-
-       if (!is_protected_kvm_enabled() || !p)
-               return;
-
-       fpsimd = &p->thread.uw.fpsimd_state;
-       kvm_unshare_hyp(fpsimd, fpsimd + 1);
-       put_task_struct(p);
-}
-
 /*
  * Called on entry to KVM_RUN unless this vcpu previously ran at least
  * once and the most recent prior KVM_RUN for this vcpu was called from
@@ -38,28 +25,18 @@ void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu)
  */
 int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
 {
-       int ret;
-
        struct user_fpsimd_state *fpsimd = &current->thread.uw.fpsimd_state;
+       int ret;
 
-       kvm_vcpu_unshare_task_fp(vcpu);
+       /* pKVM has its own tracking of the host fpsimd state. */
+       if (is_protected_kvm_enabled())
+               return 0;
 
        /* Make sure the host task fpsimd state is visible to hyp: */
        ret = kvm_share_hyp(fpsimd, fpsimd + 1);
        if (ret)
                return ret;
 
-       /*
-        * 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
-        * kernel and donated to someone else while already shared -- see
-        * kvm_vcpu_unshare_task_fp() for the matching put_task_struct().
-        */
-       if (is_protected_kvm_enabled()) {
-               get_task_struct(current);
-               vcpu->arch.parent_task = current;
-       }
-
        return 0;
 }
 

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 68d1d05672bd4fea76329c936291f9b9c37cc5d3..1b7b58cb121f98c3746da33c2d973ef49a428500 100644 (file)
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -151,7 +151,6 @@ void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
        void *sve_state = vcpu->arch.sve_state;
 
-       kvm_vcpu_unshare_task_fp(vcpu);
        kvm_unshare_hyp(vcpu, vcpu + 1);
        if (sve_state)
                kvm_unshare_hyp(sve_state, sve_state + vcpu_sve_state_size(vcpu));