Check the task's state about FP in the host and update the vcpu flags
before calling into hyp. This keeps the synchronization symmetrical
around the call into hyp.
kvm_arch_vcpu_ctxsync_fp() is renamed to kvm_arch_vcpu_sync_fp_after_hyp()
so that its name can pair with the new kvm_arch_vcpu_sync_fp_before_hyp().
If the system doesn't support FPSIMD, avoid setting any of the vcpu's
FPSIMD flags to match the previous behavior.
Signed-off-by: Andrew Scull <ascull@xxxxxxxxxx>
Cc: Dave Martin <Dave.Martin@xxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 3 ++-
arch/arm64/kvm/arm.c | 4 +++-
arch/arm64/kvm/fpsimd.c | 26 ++++++++++++++++++++++++-
arch/arm64/kvm/hyp/include/hyp/switch.h | 19 ------------------
arch/arm64/kvm/hyp/nvhe/switch.c | 3 +--
arch/arm64/kvm/hyp/vhe/switch.c | 3 +--
6 files changed, 32 insertions(+), 26 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 6b33f720ce9c..f6a478d3a902 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -726,7 +726,8 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
/* 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_ctxsync_fp(struct kvm_vcpu *vcpu);
+void kvm_arch_vcpu_sync_fp_before_hyp(struct kvm_vcpu *vcpu);
+void kvm_arch_vcpu_sync_fp_after_hyp(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu);
static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fc4c95dd2d26..26ccc369cf11 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -738,6 +738,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
local_irq_disable();
+ kvm_arch_vcpu_sync_fp_before_hyp(vcpu);
+
kvm_vgic_flush_hwstate(vcpu);
/*
@@ -825,7 +827,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
if (static_branch_unlikely(&userspace_irqchip_in_use))
kvm_timer_sync_user(vcpu);
- kvm_arch_vcpu_ctxsync_fp(vcpu);
+ kvm_arch_vcpu_sync_fp_after_hyp(vcpu);
/*
* We may have taken a host interrupt in HYP mode (ie
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 3e081d556e81..0c5e79be34d5 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -63,8 +63,13 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
BUG_ON(!current->mm);
vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
+ KVM_ARM64_FP_HOST |
KVM_ARM64_HOST_SVE_IN_USE |
KVM_ARM64_HOST_SVE_ENABLED);
+
+ if (!system_supports_fpsimd())
+ return;
+
vcpu->arch.flags |= KVM_ARM64_FP_HOST;
if (test_thread_flag(TIF_SVE))
@@ -74,13 +79,32 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
}
+
+/*
+ * If TIF_FOREIGN_FPSTATE is set, the FPSIMD regs do not contain the state of
+ * current or the guest. However, the state will have been saved where it was
+ * needed. This means the guest's state will have to be loaded if it is needed,
+ * without saving the FPSIMD regs.
+ */
+void kvm_arch_vcpu_sync_fp_before_hyp(struct kvm_vcpu *vcpu)
+{
+ WARN_ON_ONCE(!irqs_disabled());
+
+ if (!system_supports_fpsimd())
+ return;
+
+ if (test_thread_flag(TIF_FOREIGN_FPSTATE))
+ vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
+ KVM_ARM64_FP_HOST);
+}
+
/*
* 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
* so that they will be written back if the kernel clobbers them due to
* kernel-mode NEON before re-entry into the guest.
*/
-void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
+void kvm_arch_vcpu_sync_fp_after_hyp(struct kvm_vcpu *vcpu)
{
WARN_ON_ONCE(!irqs_disabled());
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 54f4860cd87c..8eb1f87f9119 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -28,31 +28,12 @@
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
#include <asm/processor.h>
-#include <asm/thread_info.h>
extern const char __hyp_panic_string[];
extern struct exception_table_entry __start___kvm_ex_table;
extern struct exception_table_entry __stop___kvm_ex_table;
-/* Check whether the FP regs were dirtied while in the host-side run loop: */
-static inline bool update_fp_enabled(struct kvm_vcpu *vcpu)
-{
- /*
- * When the system doesn't support FP/SIMD, we cannot rely on
- * the _TIF_FOREIGN_FPSTATE flag. However, we always inject an
- * abort on the very first access to FP and thus we should never
- * see KVM_ARM64_FP_ENABLED. For added safety, make sure we always
- * trap the accesses.
- */
- if (!system_supports_fpsimd() ||
- vcpu->arch.host_thread_info->flags & _TIF_FOREIGN_FPSTATE)
- vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
- KVM_ARM64_FP_HOST);
-
- return !!(vcpu->arch.flags & KVM_ARM64_FP_ENABLED);
-}
-
/* Save the 32-bit only FPSIMD system register state */
static inline void __fpsimd_save_fpexc32(struct kvm_vcpu *vcpu)
{
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index f3d0e9eca56c..6fc1e0a5adaa 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -26,7 +26,6 @@
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
#include <asm/processor.h>
-#include <asm/thread_info.h>
/* Non-VHE specific context */
DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
@@ -42,7 +41,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
val = CPTR_EL2_DEFAULT;
val |= CPTR_EL2_TTA | CPTR_EL2_TZ | CPTR_EL2_TAM;
- if (!update_fp_enabled(vcpu)) {
+ if (!(vcpu->arch.flags & KVM_ARM64_FP_ENABLED)) {
val |= CPTR_EL2_TFP;
__activate_traps_fpsimd32(vcpu);
}
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index af8e940d0f03..f6f60a537b3e 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -25,7 +25,6 @@
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
#include <asm/processor.h>
-#include <asm/thread_info.h>
const char __hyp_panic_string[] = "HYP panic:\nPS:%08llx PC:%016llx ESR:%08llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%p\n";
@@ -55,7 +54,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
val |= CPTR_EL2_TAM;
- if (update_fp_enabled(vcpu)) {
+ if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
if (vcpu_has_sve(vcpu))
val |= CPACR_EL1_ZEN;
} else {
--
2.30.1.766.gb4fecdf3b7-goog
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