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

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Date:   Wed,  4 Nov 2020 18:36:29 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Dennis Zhou <dennis@...nel.org>,
        Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Quentin Perret <qperret@...gle.com>,
        Andrew Scull <ascull@...gle.com>, kernel-team@...roid.com,
        David Brazdil <dbrazdil@...gle.com>
Subject: [RFC PATCH 25/26] kvm: arm64: Trap host SMCs

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@...gle.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