[RFC PATCH 25/26] kvm: arm64: Trap host SMCs

[David Brazdil]

While nVHE KVM is installed, start trapping all host SMCs. By default,
these are simply forwarded to EL3, but PSCI SMCs are validated first.

Create new constant HCR_HOST_NVHE_STUB_FLAGS with the old set of HCR
flags to use before the nVHE vector is installed or when switching back
to stub vector.

Extend HCR_HOST_NVHE_FLAGS to contain HCR_TSC. Set HCR_EL2 to it before
installing nVHE vector.

Signed-off-by: David Brazdil <dbrazdil at google.com>
---
 arch/arm64/include/asm/kvm_arm.h   | 3 ++-
 arch/arm64/kernel/head.S           | 2 +-
 arch/arm64/kvm/hyp/nvhe/hyp-init.S | 6 ++++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 64ce29378467..04b862955f32 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -79,7 +79,8 @@
 			 HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR | \
 			 HCR_FMO | HCR_IMO | HCR_PTW )
 #define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
-#define HCR_HOST_NVHE_FLAGS (HCR_RW | HCR_API | HCR_APK | HCR_ATA)
+#define HCR_HOST_NVHE_STUB_FLAGS (HCR_RW | HCR_API | HCR_APK | HCR_ATA)
+#define HCR_HOST_NVHE_FLAGS (HCR_HOST_NVHE_STUB_FLAGS | HCR_TSC)
 #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
 
 /* TCR_EL2 Registers bits */
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index e7270b63abed..ea17413a04e0 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -522,7 +522,7 @@ SYM_FUNC_START(el2_setup)
 #endif
 
 SYM_INNER_LABEL(el2_setup_nvhe, SYM_L_LOCAL)
-	mov_q	x0, HCR_HOST_NVHE_FLAGS
+	mov_q	x0, HCR_HOST_NVHE_STUB_FLAGS
 	msr	hcr_el2, x0
 	isb
 
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index dd297a1a8f82..97684deba6c1 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -88,6 +88,10 @@ SYM_CODE_END(__kvm_hyp_init)
  * x0: struct kvm_nvhe_init_params PA
  */
 SYM_CODE_START(___kvm_hyp_init)
+	mov_q	x1, HCR_HOST_NVHE_FLAGS
+	msr	hcr_el2, x1
+	isb
+
 	ldr	x1, [x0, #NVHE_INIT_TPIDR_EL2]
 	msr	tpidr_el2, x1
 
@@ -220,6 +224,8 @@ reset:
 	bic	x5, x5, x6		// Clear SCTL_M and etc
 	pre_disable_mmu_workaround
 	msr	sctlr_el2, x5
+	mov_q	x5, HCR_HOST_NVHE_STUB_FLAGS
+	msr	hcr_el2, x5
 	isb
 
 	/* Install stub vectors */
-- 
2.29.1.341.ge80a0c044ae-goog