KVM: arm64: Remove eager host SVE state saving

Now that the host SVE context can be saved on demand from Hyp,
there is no longer any need to save this state in advance before
entering the guest.

This patch removes the relevant call to
kvm_fpsimd_flush_cpu_state().

Since the problem that function was intended to solve now no longer
exists, the function and its dependencies are also deleted.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 3b85bbb4b23e282db8980fa28f4c469bf1089d4c..f079a2039c8ae4db669acc2d2227628720b26b01 100644 (file)
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -312,9 +312,6 @@ static inline void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) {}
 
-/* All host FP/SIMD state is restored on guest exit, so nothing to save: */
-static inline void kvm_fpsimd_flush_cpu_state(void) {}
-
 static inline void kvm_arm_vhe_guest_enter(void) {}
 static inline void kvm_arm_vhe_guest_exit(void) {}
 

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index fda9289f3b9c2458e8cd9e0929c93f4ecfec7fbf..a4ca202ff3f2a0f059d90566d18082c744ff9a06 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -457,16 +457,6 @@ static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
 }
 #endif
 
-/*
- * All host FP/SIMD state is restored on guest exit, so nothing needs
- * doing here except in the SVE case:
-*/
-static inline void kvm_fpsimd_flush_cpu_state(void)
-{
-       if (system_supports_sve())
-               sve_flush_cpu_state();
-}
-
 static inline void kvm_arm_vhe_guest_enter(void)
 {
        local_daif_mask();

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index e60c3a28380f7867c7ec6796ac9bdcb0ab4e40e2..7074c4cd0e0e1ca1533c4c8aa251be6419a45812 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -120,7 +120,6 @@
  */
 struct fpsimd_last_state_struct {
        struct user_fpsimd_state *st;
-       bool sve_in_use;
 };
 
 static DEFINE_PER_CPU(struct fpsimd_last_state_struct, fpsimd_last_state);
@@ -1008,7 +1007,6 @@ void fpsimd_bind_task_to_cpu(void)
                this_cpu_ptr(&fpsimd_last_state);
 
        last->st = &current->thread.uw.fpsimd_state;
-       last->sve_in_use = test_thread_flag(TIF_SVE);
        current->thread.fpsimd_cpu = smp_processor_id();
 
        if (system_supports_sve()) {
@@ -1030,7 +1028,6 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st)
        WARN_ON(!in_softirq() && !irqs_disabled());
 
        last->st = st;
-       last->sve_in_use = false;
 }
 
 /*
@@ -1091,24 +1088,6 @@ void fpsimd_flush_cpu_state(void)
        set_thread_flag(TIF_FOREIGN_FPSTATE);
 }
 
-/*
- * Invalidate any task SVE state currently held in this CPU's regs.
- *
- * This is used to prevent the kernel from trying to reuse SVE register data
- * that is detroyed by KVM guest enter/exit.  This function should go away when
- * KVM SVE support is implemented.  Don't use it for anything else.
- */
-#ifdef CONFIG_ARM64_SVE
-void sve_flush_cpu_state(void)
-{
-       struct fpsimd_last_state_struct const *last =
-               this_cpu_ptr(&fpsimd_last_state);
-
-       if (last->st && last->sve_in_use)
-               fpsimd_flush_cpu_state();
-}
-#endif /* CONFIG_ARM64_SVE */
-
 #ifdef CONFIG_KERNEL_MODE_NEON
 
 DEFINE_PER_CPU(bool, kernel_neon_busy);

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index ce7c6f36471b139400d14d23e63ff7bd7dd4e4d2..39e777155e7c975bf03846305ec3a097d8b98b7f 100644 (file)
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -682,9 +682,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
                 */
                preempt_disable();
 
-               /* Flush FP/SIMD state that can't survive guest entry/exit */
-               kvm_fpsimd_flush_cpu_state();
-
                kvm_pmu_flush_hwstate(vcpu);
 
                local_irq_disable();