[PATCH v10 23/59] KVM: arm64: nv: Respect virtual HCR_EL2.{NV,TSC) settings

From: Marc Zyngier <maz@kernel•org>
To: kvmarm@lists•linux.dev, kvm@vger•kernel.org,
	linux-arm-kernel@lists•infradead.org
Cc: Alexandru Elisei <alexandru.elisei@arm•com>,
	Andre Przywara <andre.przywara@arm•com>,
	Chase Conklin <chase.conklin@arm•com>,
	Christoffer Dall <christoffer.dall@arm•com>,
	Ganapatrao Kulkarni <gankulkarni@os•amperecomputing.com>,
	Darren Hart <darren@os•amperecomputing.com>,
	Jintack Lim <jintack@cs•columbia.edu>,
	Russell King <rmk+kernel@armlinux•org.uk>,
	Miguel Luis <miguel.luis@oracle•com>,
	James Morse <james.morse@arm•com>,
	Suzuki K Poulose <suzuki.poulose@arm•com>,
	Oliver Upton <oliver.upton@linux•dev>,
	Zenghui Yu <yuzenghui@huawei•com>
Subject: [PATCH v10 23/59] KVM: arm64: nv: Respect virtual HCR_EL2.{NV,TSC) settings
Date: Mon, 15 May 2023 18:30:27 +0100	[thread overview]
Message-ID: <20230515173103.1017669-24-maz@kernel.org> (raw)
In-Reply-To: <20230515173103.1017669-1-maz@kernel.org>

From: Jintack Lim <jintack.lim@linaro•org>

Forward traps due to HCR_EL2.{NV,TSC} bits to the virtual EL2 if
they are not coming from the virtual EL2, corresponding to SMC
and ERET instructions.

Signed-off-by: Jintack Lim <jintack.lim@linaro•org>
[Moved code to emulate-nested.c]
Signed-off-by: Christoffer Dall <christoffer.dall@arm•com>
[maz: drastically simplified]
Signed-off-by: Marc Zyngier <maz@kernel•org>
---
 arch/arm64/include/asm/kvm_nested.h |  1 +
 arch/arm64/kvm/emulate-nested.c     | 27 +++++++++++++++++++++++++++
 arch/arm64/kvm/handle_exit.c        |  7 +++++++
 3 files changed, 35 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 9099df57037d..948ba0337558 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -59,6 +59,7 @@ static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0)
 	return ttbr0 & ~GENMASK_ULL(63, 48);
 }
 
+extern bool forward_smc_trap(struct kvm_vcpu *vcpu);
 extern bool __check_nv_sr_forward(struct kvm_vcpu *vcpu);
 
 struct sys_reg_params;
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 101292c43602..08b152f8ba6a 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -900,6 +900,26 @@ bool __check_nv_sr_forward(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit)
+{
+	bool control_bit_set;
+
+	if (!vcpu_has_nv(vcpu))
+		return false;
+
+	control_bit_set = __vcpu_sys_reg(vcpu, HCR_EL2) & control_bit;
+	if (!vcpu_is_el2(vcpu) && control_bit_set) {
+		kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
+		return true;
+	}
+	return false;
+}
+
+bool forward_smc_trap(struct kvm_vcpu *vcpu)
+{
+	return forward_traps(vcpu, HCR_TSC);
+}
+
 static u64 kvm_check_illegal_exception_return(struct kvm_vcpu *vcpu, u64 spsr)
 {
 	u64 mode = spsr & PSR_MODE_MASK;
@@ -938,6 +958,13 @@ void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu)
 	u64 spsr, elr, mode;
 	bool direct_eret;
 
+	/*
+	 * Forward this trap to the virtual EL2 if the virtual
+	 * HCR_EL2.NV bit is set and this is coming from !EL2.
+	 */
+	if (forward_traps(vcpu, HCR_NV))
+		return;
+
 	/*
 	 * Going through the whole put/load motions is a waste of time
 	 * if this is a VHE guest hypervisor returning to its own
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index c4dc144726ee..5903102c83f5 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -55,6 +55,13 @@ static int handle_hvc(struct kvm_vcpu *vcpu)
 
 static int handle_smc(struct kvm_vcpu *vcpu)
 {
+	/*
+	 * Forward this trapped smc instruction to the virtual EL2 if
+	 * the guest has asked for it.
+	 */
+	if (forward_smc_trap(vcpu))
+		return 1;
+
 	/*
 	 * "If an SMC instruction executed at Non-secure EL1 is
 	 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
-- 
2.34.1


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