diff mbox series

[2/4] KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE

Message ID 20211021151124.3098113-3-maz@kernel.org (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Stop mapping current thread_info at EL2 | expand

Commit Message

Marc Zyngier Oct. 21, 2021, 3:11 p.m. UTC 
We currently have to maintain a mapping the thread_info structure
at EL2 in order to be able to check the TIF_FOREIGN_FPSTATE flag.

In order to eventually get rid of this, start with a vcpu flag that
shadows the thread flag on each entry into the hypervisor.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_host.h       | 2 ++
 arch/arm64/kvm/arm.c                    | 1 +
 arch/arm64/kvm/fpsimd.c                 | 8 ++++++++
 arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +-
 4 files changed, 12 insertions(+), 1 deletion(-)

Comments

Mark Brown Oct. 21, 2021, 3:24 p.m. UTC | #1 
On Thu, Oct 21, 2021 at 04:11:22PM +0100, Marc Zyngier wrote:
> We currently have to maintain a mapping the thread_info structure
> at EL2 in order to be able to check the TIF_FOREIGN_FPSTATE flag.
> 
> In order to eventually get rid of this, start with a vcpu flag that
> shadows the thread flag on each entry into the hypervisor.

Reviewed-by: Mark Brown <broonie@kernel.org>
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f856ab63f092..5a05ff062458 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -442,6 +442,7 @@  struct kvm_vcpu_arch {
 
 #define KVM_ARM64_DEBUG_STATE_SAVE_SPE	(1 << 12) /* Save SPE context if active  */
 #define KVM_ARM64_DEBUG_STATE_SAVE_TRBE	(1 << 13) /* Save TRBE context if active  */
+#define KVM_ARM64_FP_FOREIGN_FPSTATE	(1 << 14)
 
 #define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | \
 				 KVM_GUESTDBG_USE_SW_BP | \
@@ -737,6 +738,7 @@  long kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
 /* Guest/host FPSIMD coordination helpers */
 int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu);
 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);
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 24a1e86d7128..c610971c7e72 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -850,6 +850,7 @@  int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		}
 
 		kvm_arm_setup_debug(vcpu);
+		kvm_arch_vcpu_ctxflush_fp(vcpu);
 
 		/**************************************************************
 		 * Enter the guest
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 5621020b28de..12186c7d8cd8 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -86,6 +86,14 @@  void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
 		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
 }
 
+void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu)
+{
+	if (test_thread_flag(TIF_FOREIGN_FPSTATE))
+		vcpu->arch.flags |= KVM_ARM64_FP_FOREIGN_FPSTATE;
+	else
+		vcpu->arch.flags &= ~KVM_ARM64_FP_FOREIGN_FPSTATE;
+}
+
 /*
  * If the guest FPSIMD state was loaded, update the host's context
  * tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index c6e98c7e918b..dbd721a450d3 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -45,7 +45,7 @@  static inline bool update_fp_enabled(struct kvm_vcpu *vcpu)
 	 * trap the accesses.
 	 */
 	if (!system_supports_fpsimd() ||
-	    vcpu->arch.host_thread_info->flags & _TIF_FOREIGN_FPSTATE)
+	    vcpu->arch.flags & KVM_ARM64_FP_FOREIGN_FPSTATE)
 		vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
 				      KVM_ARM64_FP_HOST);