[v3,08/16] KVM: arm64: handle ITS related GICv3 redistributor registers
diff mbox

Message ID 1444229726-31559-9-git-send-email-andre.przywara@arm.com
State New
Headers show

Commit Message

Andre Przywara Oct. 7, 2015, 2:55 p.m. UTC
In the GICv3 redistributor there are the PENDBASER and PROPBASER
registers which we did not emulate so far, as they only make sense
when having an ITS. In preparation for that emulate those MMIO
accesses by storing the 64-bit data written into it into a variable
which we later read in the ITS emulation.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
Changelog v2..v3:
- rename vgic_handle_base_register to vgic_reg64_access()

 include/kvm/arm_vgic.h      |  8 ++++++++
 virt/kvm/arm/vgic-v3-emul.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic.c         | 31 +++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic.h         |  2 ++
 4 files changed, 85 insertions(+)

Comments

Pavel Fedin Oct. 22, 2015, 3:46 p.m. UTC | #1
Hello!

 During my work on live migration i found a big bug in your implementation.

> -----Original Message-----
> From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On Behalf Of Andre Przywara
> Sent: Wednesday, October 07, 2015 5:55 PM
> To: marc.zyngier@arm.com; christoffer.dall@linaro.org
> Cc: eric.auger@linaro.org; p.fedin@samsung.com; kvmarm@lists.cs.columbia.edu; linux-arm-
> kernel@lists.infradead.org; kvm@vger.kernel.org
> Subject: [PATCH v3 08/16] KVM: arm64: handle ITS related GICv3 redistributor registers
> 
> In the GICv3 redistributor there are the PENDBASER and PROPBASER
> registers which we did not emulate so far, as they only make sense
> when having an ITS. In preparation for that emulate those MMIO
> accesses by storing the 64-bit data written into it into a variable
> which we later read in the ITS emulation.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> Changelog v2..v3:
> - rename vgic_handle_base_register to vgic_reg64_access()
> 
>  include/kvm/arm_vgic.h      |  8 ++++++++
>  virt/kvm/arm/vgic-v3-emul.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  virt/kvm/arm/vgic.c         | 31 +++++++++++++++++++++++++++++++
>  virt/kvm/arm/vgic.h         |  2 ++
>  4 files changed, 85 insertions(+)
> 
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 067ad09..06c33bc 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -272,6 +272,14 @@ struct vgic_dist {
>  	/* Virtual irq to hwirq mapping */
>  	spinlock_t		irq_phys_map_lock;
>  	struct list_head	irq_phys_map_list;
> +
> +	/* Address of LPI configuration table shared by all redistributors */
> +	u64			propbaser;
> +
> +	/* Addresses of LPI pending tables per redistributor */
> +	u64			*pendbaser;
> +
> +	bool			lpis_enabled;
>  };
> 
>  struct vgic_v2_cpu_if {
> diff --git a/virt/kvm/arm/vgic-v3-emul.c b/virt/kvm/arm/vgic-v3-emul.c
> index a8cf669..6939f7c 100644
> --- a/virt/kvm/arm/vgic-v3-emul.c
> +++ b/virt/kvm/arm/vgic-v3-emul.c
> @@ -651,6 +651,38 @@ static bool handle_mmio_cfg_reg_redist(struct kvm_vcpu *vcpu,
>  	return vgic_handle_cfg_reg(reg, mmio, offset);
>  }
> 
> +/* We don't trigger any actions here, just store the register value */
> +static bool handle_mmio_propbaser_redist(struct kvm_vcpu *vcpu,
> +					 struct kvm_exit_mmio *mmio,
> +					 phys_addr_t offset)
> +{
> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> +	int mode = ACCESS_READ_VALUE;
> +
> +	/* Storing a value with LPIs already enabled is undefined */
> +	mode |= dist->lpis_enabled ? ACCESS_WRITE_IGNORED : ACCESS_WRITE_VALUE;
> +	vgic_reg64_access(mmio, offset, &dist->propbaser, mode);
> +
> +	return false;
> +}
> +
> +/* We don't trigger any actions here, just store the register value */
> +static bool handle_mmio_pendbaser_redist(struct kvm_vcpu *vcpu,
> +					 struct kvm_exit_mmio *mmio,
> +					 phys_addr_t offset)
> +{
> +	struct kvm_vcpu *rdvcpu = mmio->private;
> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> +	int mode = ACCESS_READ_VALUE;
> +
> +	/* Storing a value with LPIs already enabled is undefined */
> +	mode |= dist->lpis_enabled ? ACCESS_WRITE_IGNORED : ACCESS_WRITE_VALUE;

 Here you store lpis_enabled globally, and this is plain wrong.

 Linux kernel separately programs PENDBASER and enables LPIs on every CPU. Therefore, after CPU #0 is initialized (this happens much
earlier than everything else), dist->lpis_enabled is set to true, and subsequent PROPBASER writes, even for different
redistributors, will be ignored. As a result, you'll get dist->pendbaser[n] == NULL forever, where n > 0. And your
its_sync_lpi_pending_table() actually reads some garbage from physical address 0 of the guest.

 Attempts to write data to that region silently corrupts random qemu data during migration, that's how i discovered it.

> +	vgic_reg64_access(mmio, offset,
> +			  &dist->pendbaser[rdvcpu->vcpu_id], mode);
> +
> +	return false;
> +}
> +
>  #define SGI_base(x) ((x) + SZ_64K)
> 
>  static const struct vgic_io_range vgic_redist_ranges[] = {
> @@ -679,6 +711,18 @@ static const struct vgic_io_range vgic_redist_ranges[] = {
>  		.handle_mmio    = handle_mmio_raz_wi,
>  	},
>  	{
> +		.base		= GICR_PENDBASER,
> +		.len		= 0x08,
> +		.bits_per_irq	= 0,
> +		.handle_mmio	= handle_mmio_pendbaser_redist,
> +	},
> +	{
> +		.base		= GICR_PROPBASER,
> +		.len		= 0x08,
> +		.bits_per_irq	= 0,
> +		.handle_mmio	= handle_mmio_propbaser_redist,
> +	},
> +	{
>  		.base           = GICR_IDREGS,
>  		.len            = 0x30,
>  		.bits_per_irq   = 0,
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 4219f22..11bf692 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -471,6 +471,37 @@ void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
>  	}
>  }
> 
> +/* handle a 64-bit register access */
> +void vgic_reg64_access(struct kvm_exit_mmio *mmio, phys_addr_t offset,
> +		       u64 *basereg, int mode)
> +{
> +	u32 reg;
> +	u64 breg;
> +
> +	switch (offset & ~3) {
> +	case 0x00:
> +		breg = *basereg;
> +		reg = lower_32_bits(breg);
> +		vgic_reg_access(mmio, &reg, offset & 3, mode);
> +		if (mmio->is_write && (mode & ACCESS_WRITE_VALUE)) {
> +			breg &= GENMASK_ULL(63, 32);
> +			breg |= reg;
> +			*basereg = breg;
> +		}
> +		break;
> +	case 0x04:
> +		breg = *basereg;
> +		reg = upper_32_bits(breg);
> +		vgic_reg_access(mmio, &reg, offset & 3, mode);
> +		if (mmio->is_write && (mode & ACCESS_WRITE_VALUE)) {
> +			breg  = lower_32_bits(breg);
> +			breg |= (u64)reg << 32;
> +			*basereg = breg;
> +		}
> +		break;
> +	}
> +}
> +
>  bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
>  			phys_addr_t offset)
>  {
> diff --git a/virt/kvm/arm/vgic.h b/virt/kvm/arm/vgic.h
> index a093f5c..104f780 100644
> --- a/virt/kvm/arm/vgic.h
> +++ b/virt/kvm/arm/vgic.h
> @@ -71,6 +71,8 @@ void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
>  		     phys_addr_t offset, int mode);
>  bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
>  			phys_addr_t offset);
> +void vgic_reg64_access(struct kvm_exit_mmio *mmio, phys_addr_t offset,
> +		       u64 *basereg, int mode);
> 
>  static inline
>  u32 mmio_data_read(struct kvm_exit_mmio *mmio, u32 mask)
> --
> 2.5.1
> 
> --
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Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia


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Pavel Fedin Oct. 22, 2015, 3:55 p.m. UTC | #2
Hello!

 One more idea...

>  Here you store lpis_enabled globally, and this is plain wrong.

 By the way, may be we should move this flag, together with pendbaser array, into struct vgic_cpu? Then we would not have to
allocate them manually.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia


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Patch
diff mbox

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 067ad09..06c33bc 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -272,6 +272,14 @@  struct vgic_dist {
 	/* Virtual irq to hwirq mapping */
 	spinlock_t		irq_phys_map_lock;
 	struct list_head	irq_phys_map_list;
+
+	/* Address of LPI configuration table shared by all redistributors */
+	u64			propbaser;
+
+	/* Addresses of LPI pending tables per redistributor */
+	u64			*pendbaser;
+
+	bool			lpis_enabled;
 };
 
 struct vgic_v2_cpu_if {
diff --git a/virt/kvm/arm/vgic-v3-emul.c b/virt/kvm/arm/vgic-v3-emul.c
index a8cf669..6939f7c 100644
--- a/virt/kvm/arm/vgic-v3-emul.c
+++ b/virt/kvm/arm/vgic-v3-emul.c
@@ -651,6 +651,38 @@  static bool handle_mmio_cfg_reg_redist(struct kvm_vcpu *vcpu,
 	return vgic_handle_cfg_reg(reg, mmio, offset);
 }
 
+/* We don't trigger any actions here, just store the register value */
+static bool handle_mmio_propbaser_redist(struct kvm_vcpu *vcpu,
+					 struct kvm_exit_mmio *mmio,
+					 phys_addr_t offset)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+	int mode = ACCESS_READ_VALUE;
+
+	/* Storing a value with LPIs already enabled is undefined */
+	mode |= dist->lpis_enabled ? ACCESS_WRITE_IGNORED : ACCESS_WRITE_VALUE;
+	vgic_reg64_access(mmio, offset, &dist->propbaser, mode);
+
+	return false;
+}
+
+/* We don't trigger any actions here, just store the register value */
+static bool handle_mmio_pendbaser_redist(struct kvm_vcpu *vcpu,
+					 struct kvm_exit_mmio *mmio,
+					 phys_addr_t offset)
+{
+	struct kvm_vcpu *rdvcpu = mmio->private;
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+	int mode = ACCESS_READ_VALUE;
+
+	/* Storing a value with LPIs already enabled is undefined */
+	mode |= dist->lpis_enabled ? ACCESS_WRITE_IGNORED : ACCESS_WRITE_VALUE;
+	vgic_reg64_access(mmio, offset,
+			  &dist->pendbaser[rdvcpu->vcpu_id], mode);
+
+	return false;
+}
+
 #define SGI_base(x) ((x) + SZ_64K)
 
 static const struct vgic_io_range vgic_redist_ranges[] = {
@@ -679,6 +711,18 @@  static const struct vgic_io_range vgic_redist_ranges[] = {
 		.handle_mmio    = handle_mmio_raz_wi,
 	},
 	{
+		.base		= GICR_PENDBASER,
+		.len		= 0x08,
+		.bits_per_irq	= 0,
+		.handle_mmio	= handle_mmio_pendbaser_redist,
+	},
+	{
+		.base		= GICR_PROPBASER,
+		.len		= 0x08,
+		.bits_per_irq	= 0,
+		.handle_mmio	= handle_mmio_propbaser_redist,
+	},
+	{
 		.base           = GICR_IDREGS,
 		.len            = 0x30,
 		.bits_per_irq   = 0,
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 4219f22..11bf692 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -471,6 +471,37 @@  void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
 	}
 }
 
+/* handle a 64-bit register access */
+void vgic_reg64_access(struct kvm_exit_mmio *mmio, phys_addr_t offset,
+		       u64 *basereg, int mode)
+{
+	u32 reg;
+	u64 breg;
+
+	switch (offset & ~3) {
+	case 0x00:
+		breg = *basereg;
+		reg = lower_32_bits(breg);
+		vgic_reg_access(mmio, &reg, offset & 3, mode);
+		if (mmio->is_write && (mode & ACCESS_WRITE_VALUE)) {
+			breg &= GENMASK_ULL(63, 32);
+			breg |= reg;
+			*basereg = breg;
+		}
+		break;
+	case 0x04:
+		breg = *basereg;
+		reg = upper_32_bits(breg);
+		vgic_reg_access(mmio, &reg, offset & 3, mode);
+		if (mmio->is_write && (mode & ACCESS_WRITE_VALUE)) {
+			breg  = lower_32_bits(breg);
+			breg |= (u64)reg << 32;
+			*basereg = breg;
+		}
+		break;
+	}
+}
+
 bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
 			phys_addr_t offset)
 {
diff --git a/virt/kvm/arm/vgic.h b/virt/kvm/arm/vgic.h
index a093f5c..104f780 100644
--- a/virt/kvm/arm/vgic.h
+++ b/virt/kvm/arm/vgic.h
@@ -71,6 +71,8 @@  void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
 		     phys_addr_t offset, int mode);
 bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
 			phys_addr_t offset);
+void vgic_reg64_access(struct kvm_exit_mmio *mmio, phys_addr_t offset,
+		       u64 *basereg, int mode);
 
 static inline
 u32 mmio_data_read(struct kvm_exit_mmio *mmio, u32 mask)