From f174a9ffcd48d78a45d560c02ce4071ded036b53 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 19 Jan 2026 10:29:22 +0800 Subject: KVM: arm64: Add exit to userspace on {LD,ST}64B* outside of memslots The main use of {LD,ST}64B* is to talk to a device, which is hopefully directly assigned to the guest and requires no additional handling. However, this does not preclude a VMM from exposing a virtual device to the guest, and to allow 64 byte accesses as part of the programming interface. A direct consequence of this is that we need to be able to forward such access to userspace. Given that such a contraption is very unlikely to ever exist, we choose to offer a limited service: userspace gets (as part of a new exit reason) the ESR, the IPA, and that's it. It is fully expected to handle the full semantics of the instructions, deal with ACCDATA, the return values and increment PC. Much fun. A canonical implementation can also simply inject an abort and be done with it. Frankly, don't try to do anything else unless you have time to waste. Acked-by: Arnd Bergmann Acked-by: Oliver Upton Signed-off-by: Marc Zyngier Signed-off-by: Yicong Yang Signed-off-by: Zhou Wang Signed-off-by: Will Deacon --- include/uapi/linux/kvm.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index dddb781b0507..88cca0e22ece 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -180,6 +180,7 @@ struct kvm_xen_exit { #define KVM_EXIT_MEMORY_FAULT 39 #define KVM_EXIT_TDX 40 #define KVM_EXIT_ARM_SEA 41 +#define KVM_EXIT_ARM_LDST64B 42 /* For KVM_EXIT_INTERNAL_ERROR */ /* Emulate instruction failed. */ @@ -402,7 +403,7 @@ struct kvm_run { } eoi; /* KVM_EXIT_HYPERV */ struct kvm_hyperv_exit hyperv; - /* KVM_EXIT_ARM_NISV */ + /* KVM_EXIT_ARM_NISV / KVM_EXIT_ARM_LDST64B */ struct { __u64 esr_iss; __u64 fault_ipa; -- cgit v1.2.3 From 3227c3a89d65fe7482312b7b27038d9ebd86f210 Mon Sep 17 00:00:00 2001 From: Sascha Bischoff Date: Wed, 28 Jan 2026 18:07:33 +0000 Subject: irqchip/gic-v5: Check if impl is virt capable Now that there is support for creating a GICv5-based guest with KVM, check that the hardware itself supports virtualisation, skipping the setting of struct gic_kvm_info if not. Note: If native GICv5 virt is not supported, then nor is FEAT_GCIE_LEGACY, so we are able to skip altogether. Signed-off-by: Sascha Bischoff Reviewed-by: Lorenzo Pieralisi Reviewed-by: Jonathan Cameron Link: https://patch.msgid.link/20260128175919.3828384-33-sascha.bischoff@arm.com [maz: cosmetic changes] Signed-off-by: Marc Zyngier --- include/linux/irqchip/arm-gic-v5.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/irqchip/arm-gic-v5.h b/include/linux/irqchip/arm-gic-v5.h index 68ddcdb1cec5..4cb71ce6e8ad 100644 --- a/include/linux/irqchip/arm-gic-v5.h +++ b/include/linux/irqchip/arm-gic-v5.h @@ -43,6 +43,7 @@ /* * IRS registers and tables structures */ +#define GICV5_IRS_IDR0 0x0000 #define GICV5_IRS_IDR1 0x0004 #define GICV5_IRS_IDR2 0x0008 #define GICV5_IRS_IDR5 0x0014 @@ -63,6 +64,8 @@ #define GICV5_IRS_IST_STATUSR 0x0194 #define GICV5_IRS_MAP_L2_ISTR 0x01c0 +#define GICV5_IRS_IDR0_VIRT BIT(6) + #define GICV5_IRS_IDR1_PRIORITY_BITS GENMASK(22, 20) #define GICV5_IRS_IDR1_IAFFID_BITS GENMASK(19, 16) @@ -278,6 +281,7 @@ struct gicv5_chip_data { u8 cpuif_pri_bits; u8 cpuif_id_bits; u8 irs_pri_bits; + bool virt_capable; struct { __le64 *l1ist_addr; u32 l2_size; -- cgit v1.2.3 From 5ab24969705a9adadbc1d3cff4c1c15df174eafb Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Mon, 2 Feb 2026 08:57:20 +0000 Subject: KVM: arm64: Reimplement vgic-debug XArray iteration The vgic-debug interface implementation uses XArray marks (`LPI_XA_MARK_DEBUG_ITER`) to "snapshot" LPIs at the start of iteration. This modifies global state for a read-only operation and complicates reference counting, leading to leaks if iteration is aborted or fails. Reimplement the iterator to use dynamic iteration logic: - Remove `lpi_idx` from `struct vgic_state_iter`. - Replace the XArray marking mechanism with dynamic iteration using `xa_find_after(..., XA_PRESENT)`. - Wrap XArray traversals in `rcu_read_lock()`/`rcu_read_unlock()` to ensure safety against concurrent modifications (e.g., LPI unmapping). - Handle potential races where an LPI is removed during iteration by gracefully skipping it in `show()`, rather than warning. - Remove the unused `LPI_XA_MARK_DEBUG_ITER` definition. This simplifies the lifecycle management of the iterator and prevents resource leaks associated with the marking mechanism, and paves the way for using a standard seq_file iterator. Signed-off-by: Fuad Tabba Link: https://patch.msgid.link/20260202085721.3954942-3-tabba@google.com Signed-off-by: Marc Zyngier --- include/kvm/arm_vgic.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index b261fb3968d0..d32fafbd2907 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -300,7 +300,6 @@ struct vgic_dist { */ u64 propbaser; -#define LPI_XA_MARK_DEBUG_ITER XA_MARK_0 struct xarray lpi_xa; /* used by vgic-debug */ -- cgit v1.2.3 From fb21cb08566ebed91d5c876db5c013cc8af83b89 Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Mon, 2 Feb 2026 08:57:21 +0000 Subject: KVM: arm64: Use standard seq_file iterator for vgic-debug debugfs The current implementation uses `vgic_state_iter` in `struct vgic_dist` to track the sequence position. This effectively makes the iterator shared across all open file descriptors for the VM. This approach has significant drawbacks: - It enforces mutual exclusion, preventing concurrent reads of the debugfs file (returning -EBUSY). - It relies on storing transient iterator state in the long-lived VM structure (`vgic_dist`). Refactor the implementation to use the standard `seq_file` iterator. Instead of storing state in `kvm_arch`, rely on the `pos` argument passed to the `start` and `next` callbacks, which tracks the logical index specific to the file descriptor. This change enables concurrent access and eliminates the `vgic_state_iter` field from `struct vgic_dist`. Signed-off-by: Fuad Tabba Link: https://patch.msgid.link/20260202085721.3954942-4-tabba@google.com Signed-off-by: Marc Zyngier --- include/kvm/arm_vgic.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include') diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index d32fafbd2907..f2eafc65bbf4 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -302,9 +302,6 @@ struct vgic_dist { struct xarray lpi_xa; - /* used by vgic-debug */ - struct vgic_state_iter *iter; - /* * GICv4 ITS per-VM data, containing the IRQ domain, the VPE * array, the property table pointer as well as allocation -- cgit v1.2.3