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From: Fabiano Rosas <farosas@linux.ibm.com>
To: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com
Subject: [PATCH v4 2/2] KVM: PPC: Book3S HV: Stop forwarding all HFUs to L1
Date: Thu, 22 Jul 2021 19:12:40 -0300	[thread overview]
Message-ID: <20210722221240.2384655-3-farosas@linux.ibm.com> (raw)
In-Reply-To: <20210722221240.2384655-1-farosas@linux.ibm.com>

If the nested hypervisor has no access to a facility because it has
been disabled by the host, it should also not be able to see the
Hypervisor Facility Unavailable that arises from one of its guests
trying to access the facility.

This patch turns a HFU that happened in L2 into a Hypervisor Emulation
Assistance interrupt and forwards it to L1 for handling. The ones that
happened because L1 explicitly disabled the facility for L2 are still
let through, along with the corresponding Cause bits in the HFSCR.

Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
---
 arch/powerpc/kvm/book3s_hv_nested.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
index 3804dc50ebe8..d171a400e4d5 100644
--- a/arch/powerpc/kvm/book3s_hv_nested.c
+++ b/arch/powerpc/kvm/book3s_hv_nested.c
@@ -99,7 +99,7 @@ static void byteswap_hv_regs(struct hv_guest_state *hr)
 	hr->dawrx1 = swab64(hr->dawrx1);
 }
 
-static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
+static void save_hv_return_state(struct kvm_vcpu *vcpu,
 				 struct hv_guest_state *hr)
 {
 	struct kvmppc_vcore *vc = vcpu->arch.vcore;
@@ -128,7 +128,7 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
 	hr->pidr = vcpu->arch.pid;
 	hr->cfar = vcpu->arch.cfar;
 	hr->ppr = vcpu->arch.ppr;
-	switch (trap) {
+	switch (vcpu->arch.trap) {
 	case BOOK3S_INTERRUPT_H_DATA_STORAGE:
 		hr->hdar = vcpu->arch.fault_dar;
 		hr->hdsisr = vcpu->arch.fault_dsisr;
@@ -137,6 +137,27 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
 	case BOOK3S_INTERRUPT_H_INST_STORAGE:
 		hr->asdr = vcpu->arch.fault_gpa;
 		break;
+	case BOOK3S_INTERRUPT_H_FAC_UNAVAIL:
+	{
+		u8 cause = vcpu->arch.hfscr >> 56;
+
+		WARN_ON_ONCE(cause >= BITS_PER_LONG);
+
+		if (!(hr->hfscr & (1UL << cause)))
+			break;
+
+		/*
+		 * We have disabled this facility, so it does not
+		 * exist from L1's perspective. Turn it into a HEAI.
+		 */
+		vcpu->arch.trap = BOOK3S_INTERRUPT_H_EMUL_ASSIST;
+		kvmppc_load_last_inst(vcpu, INST_GENERIC, &vcpu->arch.emul_inst);
+
+		/* Don't leak the cause field */
+		hr->hfscr &= ~HFSCR_INTR_CAUSE;
+
+		fallthrough;
+	}
 	case BOOK3S_INTERRUPT_H_EMUL_ASSIST:
 		hr->heir = vcpu->arch.emul_inst;
 		break;
@@ -374,7 +395,7 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
 	delta_spurr = vcpu->arch.spurr - l2_hv.spurr;
 	delta_ic = vcpu->arch.ic - l2_hv.ic;
 	delta_vtb = vc->vtb - l2_hv.vtb;
-	save_hv_return_state(vcpu, vcpu->arch.trap, &l2_hv);
+	save_hv_return_state(vcpu, &l2_hv);
 
 	/* restore L1 state */
 	vcpu->arch.nested = NULL;
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Fabiano Rosas <farosas@linux.ibm.com>
To: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com
Subject: [PATCH v4 2/2] KVM: PPC: Book3S HV: Stop forwarding all HFUs to L1
Date: Thu, 22 Jul 2021 22:12:40 +0000	[thread overview]
Message-ID: <20210722221240.2384655-3-farosas@linux.ibm.com> (raw)
In-Reply-To: <20210722221240.2384655-1-farosas@linux.ibm.com>

If the nested hypervisor has no access to a facility because it has
been disabled by the host, it should also not be able to see the
Hypervisor Facility Unavailable that arises from one of its guests
trying to access the facility.

This patch turns a HFU that happened in L2 into a Hypervisor Emulation
Assistance interrupt and forwards it to L1 for handling. The ones that
happened because L1 explicitly disabled the facility for L2 are still
let through, along with the corresponding Cause bits in the HFSCR.

Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
---
 arch/powerpc/kvm/book3s_hv_nested.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
index 3804dc50ebe8..d171a400e4d5 100644
--- a/arch/powerpc/kvm/book3s_hv_nested.c
+++ b/arch/powerpc/kvm/book3s_hv_nested.c
@@ -99,7 +99,7 @@ static void byteswap_hv_regs(struct hv_guest_state *hr)
 	hr->dawrx1 = swab64(hr->dawrx1);
 }
 
-static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
+static void save_hv_return_state(struct kvm_vcpu *vcpu,
 				 struct hv_guest_state *hr)
 {
 	struct kvmppc_vcore *vc = vcpu->arch.vcore;
@@ -128,7 +128,7 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
 	hr->pidr = vcpu->arch.pid;
 	hr->cfar = vcpu->arch.cfar;
 	hr->ppr = vcpu->arch.ppr;
-	switch (trap) {
+	switch (vcpu->arch.trap) {
 	case BOOK3S_INTERRUPT_H_DATA_STORAGE:
 		hr->hdar = vcpu->arch.fault_dar;
 		hr->hdsisr = vcpu->arch.fault_dsisr;
@@ -137,6 +137,27 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
 	case BOOK3S_INTERRUPT_H_INST_STORAGE:
 		hr->asdr = vcpu->arch.fault_gpa;
 		break;
+	case BOOK3S_INTERRUPT_H_FAC_UNAVAIL:
+	{
+		u8 cause = vcpu->arch.hfscr >> 56;
+
+		WARN_ON_ONCE(cause >= BITS_PER_LONG);
+
+		if (!(hr->hfscr & (1UL << cause)))
+			break;
+
+		/*
+		 * We have disabled this facility, so it does not
+		 * exist from L1's perspective. Turn it into a HEAI.
+		 */
+		vcpu->arch.trap = BOOK3S_INTERRUPT_H_EMUL_ASSIST;
+		kvmppc_load_last_inst(vcpu, INST_GENERIC, &vcpu->arch.emul_inst);
+
+		/* Don't leak the cause field */
+		hr->hfscr &= ~HFSCR_INTR_CAUSE;
+
+		fallthrough;
+	}
 	case BOOK3S_INTERRUPT_H_EMUL_ASSIST:
 		hr->heir = vcpu->arch.emul_inst;
 		break;
@@ -374,7 +395,7 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
 	delta_spurr = vcpu->arch.spurr - l2_hv.spurr;
 	delta_ic = vcpu->arch.ic - l2_hv.ic;
 	delta_vtb = vc->vtb - l2_hv.vtb;
-	save_hv_return_state(vcpu, vcpu->arch.trap, &l2_hv);
+	save_hv_return_state(vcpu, &l2_hv);
 
 	/* restore L1 state */
 	vcpu->arch.nested = NULL;
-- 
2.29.2

  parent reply	other threads:[~2021-07-22 22:13 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-22 22:12 [PATCH v4 0/2] KVM: PPC: Book3S HV: Nested guest state sanitising changes Fabiano Rosas
2021-07-22 22:12 ` Fabiano Rosas
2021-07-22 22:12 ` [PATCH v4 1/2] KVM: PPC: Book3S HV: Sanitise vcpu registers in nested path Fabiano Rosas
2021-07-22 22:12   ` Fabiano Rosas
2021-07-26  1:50   ` Nicholas Piggin
2021-07-26  1:50     ` Nicholas Piggin
2021-07-22 22:12 ` Fabiano Rosas [this message]
2021-07-22 22:12   ` [PATCH v4 2/2] KVM: PPC: Book3S HV: Stop forwarding all HFUs to L1 Fabiano Rosas

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