[PATCH v2 4/5] KVM: arm64: Exclude host_fpsimd_state pointer from kvm_vcpu_arch

Marc Zyngier
2024-03-22T17:10:09Z

As the name of the field indicates, host_fpsimd_state is strictly
a host piece of data, and we reset this pointer on each PID change.

So let's move it where it belongs, and set it at load-time. Although
this is slightly more often, it is a well defined life-cycle which
matches other pieces of data.

Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 2 +-
arch/arm64/kvm/fpsimd.c | 3 +--
arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 1 -
4 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 590e8767b720..838cdee2ecf7 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -543,6 +543,7 @@ struct kvm_cpu_context {
*/
struct kvm_host_data {
struct kvm_cpu_context host_ctxt;
+ struct user_fpsimd_state *fpsimd_state; /* hyp VA */

/*
* host_debug_state contains the host registers which are
@@ -661,7 +662,6 @@ 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;

/* VGIC state */
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 571cf6eef1e1..e6bd99358615 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -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
@@ -87,6 +85,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
* FP_STATE_FREE if the flag set.
*/
vcpu->arch.fp_state = FP_STATE_HOST_OWNED;
+ *host_data_ptr(fpsimd_state) = kern_hyp_va(&current->thread.uw.fpsimd_state);

vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 7d7de0245ed0..6def6ad8dd48 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -377,7 +377,7 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)

/* 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);
+ __fpsimd_save_state(*host_data_ptr(fpsimd_state));

/* Restore the guest state */
if (sve_guest)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 2385fd03ed87..c5f625dc1f07 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -42,7 +42,6 @@ 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;

--
2.39.2