* [PATCH 1/2] KVM: arm64: Correctly align nVHE percpu data
2020-11-27 11:20 [GIT PULL] KVM/arm64 fixes for 5.10, take #4 Marc Zyngier
@ 2020-11-27 11:21 ` Marc Zyngier
2020-11-27 11:21 ` [PATCH 2/2] KVM: arm64: vgic-v3: Drop the reporting of GICR_TYPER.Last for userspace Marc Zyngier
1 sibling, 0 replies; 3+ messages in thread
From: Marc Zyngier @ 2020-11-27 11:21 UTC (permalink / raw)
To: Paolo Bonzini
Cc: kernel-team, kvm, Suzuki K Poulose, Will Deacon, Jamie Iles,
Eric Auger, James Morse, linux-arm-kernel, Zenghui Yu,
David Brazdil, Keqian Zhu, kvmarm, Julien Thierry
From: Jamie Iles <jamie@nuviainc.com>
The nVHE percpu data is partially linked but the nVHE linker script did
not align the percpu section. The PERCPU_INPUT macro would then align
the data to a page boundary:
#define PERCPU_INPUT(cacheline) \
__per_cpu_start = .; \
*(.data..percpu..first) \
. = ALIGN(PAGE_SIZE); \
*(.data..percpu..page_aligned) \
. = ALIGN(cacheline); \
*(.data..percpu..read_mostly) \
. = ALIGN(cacheline); \
*(.data..percpu) \
*(.data..percpu..shared_aligned) \
PERCPU_DECRYPTED_SECTION \
__per_cpu_end = .;
but then when the final vmlinux linking happens the hypervisor percpu
data is included after page alignment and so the offsets potentially
don't match. On my build I saw that the .hyp.data..percpu section was
at address 0x20 and then the percpu data would begin at 0x1000 (because
of the page alignment in PERCPU_INPUT), but when linked into vmlinux,
everything would be shifted down by 0x20 bytes.
This manifests as one of the CPUs getting lost when running
kvm-unit-tests or starting any VM and subsequent soft lockup on a Cortex
A72 device.
Fixes: 30c953911c43 ("kvm: arm64: Set up hyp percpu data for nVHE")
Signed-off-by: Jamie Iles <jamie@nuviainc.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Cc: David Brazdil <dbrazdil@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201113150406.14314-1-jamie@nuviainc.com
---
arch/arm64/kvm/hyp/nvhe/hyp.lds.S | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
index bb2d986ff696..a797abace13f 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
@@ -13,6 +13,11 @@
SECTIONS {
HYP_SECTION(.text)
+ /*
+ * .hyp..data..percpu needs to be page aligned to maintain the same
+ * alignment for when linking into vmlinux.
+ */
+ . = ALIGN(PAGE_SIZE);
HYP_SECTION_NAME(.data..percpu) : {
PERCPU_INPUT(L1_CACHE_BYTES)
}
--
2.28.0
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^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] KVM: arm64: vgic-v3: Drop the reporting of GICR_TYPER.Last for userspace
2020-11-27 11:20 [GIT PULL] KVM/arm64 fixes for 5.10, take #4 Marc Zyngier
2020-11-27 11:21 ` [PATCH 1/2] KVM: arm64: Correctly align nVHE percpu data Marc Zyngier
@ 2020-11-27 11:21 ` Marc Zyngier
1 sibling, 0 replies; 3+ messages in thread
From: Marc Zyngier @ 2020-11-27 11:21 UTC (permalink / raw)
To: Paolo Bonzini
Cc: kernel-team, kvm, Suzuki K Poulose, Will Deacon, Jamie Iles,
stable, Eric Auger, James Morse, linux-arm-kernel, Zenghui Yu,
David Brazdil, Keqian Zhu, kvmarm, Julien Thierry
From: Zenghui Yu <yuzenghui@huawei.com>
It was recently reported that if GICR_TYPER is accessed before the RD base
address is set, we'll suffer from the unset @rdreg dereferencing. Oops...
gpa_t last_rdist_typer = rdreg->base + GICR_TYPER +
(rdreg->free_index - 1) * KVM_VGIC_V3_REDIST_SIZE;
It's "expected" that users will access registers in the redistributor if
the RD has been properly configured (e.g., the RD base address is set). But
it hasn't yet been covered by the existing documentation.
Per discussion on the list [1], the reporting of the GICR_TYPER.Last bit
for userspace never actually worked. And it's difficult for us to emulate
it correctly given that userspace has the flexibility to access it any
time. Let's just drop the reporting of the Last bit for userspace for now
(userspace should have full knowledge about it anyway) and it at least
prevents kernel from panic ;-)
[1] https://lore.kernel.org/kvmarm/c20865a267e44d1e2c0d52ce4e012263@kernel.org/
Fixes: ba7b3f1275fd ("KVM: arm/arm64: Revisit Redistributor TYPER last bit computation")
Reported-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20201117151629.1738-1-yuzenghui@huawei.com
Cc: stable@vger.kernel.org
---
arch/arm64/kvm/vgic/vgic-mmio-v3.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 52d6f24f65dc..15a6c98ee92f 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -273,6 +273,23 @@ static unsigned long vgic_mmio_read_v3r_typer(struct kvm_vcpu *vcpu,
return extract_bytes(value, addr & 7, len);
}
+static unsigned long vgic_uaccess_read_v3r_typer(struct kvm_vcpu *vcpu,
+ gpa_t addr, unsigned int len)
+{
+ unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu);
+ int target_vcpu_id = vcpu->vcpu_id;
+ u64 value;
+
+ value = (u64)(mpidr & GENMASK(23, 0)) << 32;
+ value |= ((target_vcpu_id & 0xffff) << 8);
+
+ if (vgic_has_its(vcpu->kvm))
+ value |= GICR_TYPER_PLPIS;
+
+ /* reporting of the Last bit is not supported for userspace */
+ return extract_bytes(value, addr & 7, len);
+}
+
static unsigned long vgic_mmio_read_v3r_iidr(struct kvm_vcpu *vcpu,
gpa_t addr, unsigned int len)
{
@@ -593,8 +610,9 @@ static const struct vgic_register_region vgic_v3_rd_registers[] = {
REGISTER_DESC_WITH_LENGTH(GICR_IIDR,
vgic_mmio_read_v3r_iidr, vgic_mmio_write_wi, 4,
VGIC_ACCESS_32bit),
- REGISTER_DESC_WITH_LENGTH(GICR_TYPER,
- vgic_mmio_read_v3r_typer, vgic_mmio_write_wi, 8,
+ REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_TYPER,
+ vgic_mmio_read_v3r_typer, vgic_mmio_write_wi,
+ vgic_uaccess_read_v3r_typer, vgic_mmio_uaccess_write_wi, 8,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_DESC_WITH_LENGTH(GICR_WAKER,
vgic_mmio_read_raz, vgic_mmio_write_wi, 4,
--
2.28.0
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^ permalink raw reply related [flat|nested] 3+ messages in thread