This patch only saves and restores FP/SIMD registers on Guest access. To do
this cptr_el2 FP/SIMD trap is set on Guest entry and later checked on exit.
The non-VHE path has been tested, future work would add VHE support.
Signed-off-by: Mario Smarduch <m.smard...@samsung.com>
---
arch/arm64/include/asm/kvm_arm.h | 5 +++-
arch/arm64/kvm/hyp.S | 58 +++++++++++++++++++++++++++++++++++++---
2 files changed, 58 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index c8998c0..0a1d152 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -172,10 +172,13 @@
#define HSTR_EL2_TTEE (1 << 16)
#define HSTR_EL2_T(x) (1 << x)
+/* Hyp Coproccessor Trap Register Shifts */
+#define CPTR_EL2_TFP_SHIFT 10
+
/* Hyp Coprocessor Trap Register */
#define CPTR_EL2_TCPAC (1 << 31)
#define CPTR_EL2_TTA (1 << 20)
-#define CPTR_EL2_TFP (1 << 10)
+#define CPTR_EL2_TFP (1 << CPTR_EL2_TFP_SHIFT)
/* Hyp Debug Configuration Register bits */
#define MDCR_EL2_TDRA (1 << 11)
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 64a5280..9d154ed 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -731,6 +731,15 @@ ifnvhe "mrs \tmp, hcr_el2", _S_(ldr
\tmp, [x0, #VCPU_HCR_EL2])
tbz \tmp, #KVM_ARM64_DEBUG_DIRTY_SHIFT, \target
.endm
+/*
+ * For non-VHE - branch to target if CPTR_EL2.TFP bit is set (VFP/SIMD trapping
+ * enabled). For VHE do nothing.
+ */
+.macro skip_fpsimd_state tmp, target
+ifnvhe "mrs \tmp, cptr_el2", nop
+ifnvhe _S_(tbnz \tmp, #CPTR_EL2_TFP_SHIFT, \target), nop
+.endm
+
.macro compute_debug_state target
// Compute debug state: If any of KDE, MDE or KVM_ARM64_DEBUG_DIRTY
// is set, we do a full save/restore cycle and disable trapping.
@@ -823,7 +832,7 @@ ifnvhe "mrs \tmp, hcr_el2", _S_(ldr \tmp,
[x0, #VCPU_HCR_EL2])
adr x3, __kvm_hyp_vector
ifnvhe nop, "msr vbar_el1, x3"
ifnvhe nop, "mrs x2, cpacr_el1"
-ifnvhe _S_(ldr x2, =(CPTR_EL2_TTA)), "orr x2, x2, #(1 << 28)"
+ifnvhe _S_(ldr x2, =(CPTR_EL2_TTA|CPTR_EL2_TFP)), "orr x2, x2, #(1 << 28)"
ifnvhe "msr cptr_el2, x2", "msr cpacr_el1, x2"
mov x2, #(1 << 15) // Trap CP15 Cr=15
@@ -851,7 +860,7 @@ ifnvhe nop, _S_(orr
x2, x2, #HCR_E2H)
ifnvhe nop, "mrs x2, cpacr_el1"
ifnvhe nop, "movn x3, #(1 << 12), lsl #16"
ifnvhe nop, "and x2, x2, x3"
-ifnvhe "msr cptr_el2, xzr", "msr cpacr_el1, x2"
+ifnvhe nop, "msr cpacr_el1, x2"
msr hstr_el2, xzr
mrs x2, mdcr_el2
@@ -988,6 +997,33 @@ __restore_fpsimd:
ret
/*
+ * For non-VHE - on first FP/SIMD access, restore guest, save host registers
+ * and disable future trapping. For VHE this should never get called.
+ */
+switch_to_guest_fpsimd:
+ push x4, lr
+
+ mrs x2, cptr_el2
+ bic x2, x2, #CPTR_EL2_TFP
+ msr cptr_el2, x2
+
+ mrs x0, tpidr_el2
+
+ ldr x2, [x0, #VCPU_HOST_CONTEXT]
+ kern_hyp_va x2
+ bl __save_fpsimd
+
+ add x2, x0, #VCPU_CONTEXT
+ bl __restore_fpsimd
+
+ pop x4, lr
+ pop x2, x3
+ pop x0, x1
+
+ eret
+
+
+/*
* u64 __kvm_vcpu_run(struct kvm_vcpu *vcpu);
*
* This is the world switch. The first half of the function
@@ -1007,7 +1043,7 @@ ENTRY(__kvm_vcpu_run)
kern_hyp_va x2
save_host_regs
- bl __save_fpsimd
+ifnvhe nop, "bl __save_fpsimd"
ifnvhe "bl __save_sysregs", "nop"
bl __save_shared_sysregs
@@ -1025,7 +1061,7 @@ ifnvhe "bl __save_sysregs", "nop"
bl __restore_sysregs
bl __restore_shared_sysregs
- bl __restore_fpsimd
+ifnvhe "nop", "bl __restore_fpsimd"
skip_debug_state x3, 1f
bl __restore_debug
@@ -1044,7 +1080,9 @@ __kvm_vcpu_return:
add x2, x0, #VCPU_CONTEXT
save_guest_regs
+ skip_fpsimd_state x3, 1f
bl __save_fpsimd
+1:
bl __save_sysregs
bl __save_shared_sysregs
@@ -1072,7 +1110,11 @@ __kvm_vcpu_return_irq:
ifnvhe "bl __restore_sysregs", "nop"
bl __restore_shared_sysregs
+ skip_fpsimd_state x3, 1f
bl __restore_fpsimd
+1:
+ /* For non-VHE - Clear FPSIMD and Trace trapping, do nothig for VHE */
+ifnvhe "msr cptr_el2, xzr", "nop"
skip_debug_state x3, 1f
// Clear the dirty flag for the next run, as all the state has
@@ -1298,6 +1340,14 @@ el1_trap:
* x1: ESR
* x2: ESR_EC
*/
+
+ /*
+ * For non-VHE Guest accessed FP/SIMD registers, save host, restore
+ * guest. For VHE condition should never be true.
+ */
+ cmp x2, #ESR_ELx_EC_FP_ASIMD
+ b.eq switch_to_guest_fpsimd
+
cmp x2, #ESR_ELx_EC_DABT_LOW
mov x0, #ESR_ELx_EC_IABT_LOW
ccmp x2, x0, #4, ne
--
1.9.1
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