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Currently, the common AIA functions kvm_riscv_vcpu_aia_has_interrupts()
and kvm_riscv_aia_wakeon_hgei() lookup HGEI line using an array of VCPU
pointers before accessing HGEI[E|P] CSR which is slow and prone to race
conditions because there is a separate per-hart lock for the VCPU pointer
array and a separate per-VCPU rwlock for IMSIC VS-file (including HGEI
line) used by the VCPU. Due to these race conditions, it is observed
on QEMU RISC-V host that Guest VCPUs sleep in WFI and never wakeup even
with interrupt pending in the IMSIC VS-file because VCPUs were waiting
for HGEI wakeup on the wrong host CPU.
The IMSIC virtualization already keeps track of the HGEI line and the
associated IMSIC VS-file used by each VCPU so move the HGEI[E|P] CSR
access to IMSIC virtualization so that costly HGEI line lookup can be
avoided and likelihood of race-conditions when updating HGEI[E|P] CSR
is also reduced.
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>
Tested-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Fixes: 3385339296d1 ("RISC-V: KVM: Use IMSIC guest files when available")
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>
Link: https://lore.kernel.org/r/20250707035345.17494-3-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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The SBI reset state has only two variables -- pc and a1.
The rest is known, so keep only the necessary information.
The reset structures make sense if we want userspace to control the
reset state (which we do), but I'd still remove them now and reintroduce
with the userspace interface later -- we could probably have just a
single reset state per VM, instead of a reset state for each VCPU.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
Link: https://lore.kernel.org/r/20250403112522.1566629-6-rkrcmar@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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We expose IMSIC registers as KVM device attributes of the in-kernel
AIA irqchip device. This will allow KVM user-space to save/restore
IMISC state of each VCPU using KVM device ioctls().
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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We can have AIA IMSIC support for both HS-level and VS-level but
the VS-level IMSICs are optional. We use the VS-level IMSICs for
Guest/VM whenever available otherwise we fallback to software
emulation of AIA IMSIC.
This patch adds in-kernel virtualization of AIA IMSIC.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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We expose APLIC registers as KVM device attributes of the in-kernel
AIA irqchip device. This will allow KVM user-space to save/restore
APLIC state using KVM device ioctls().
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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There is no virtualization support in AIA APLIC so we add in-kernel
emulation of AIA APLIC which only supports MSI-mode (i.e. wired
interrupts forwarded to AIA IMSIC as MSIs).
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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We implement KVM device interface for in-kernel AIA irqchip so that
user-space can use KVM device ioctls to create, configure, and destroy
in-kernel AIA irqchip.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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To incrementally implement in-kernel AIA irqchip support, we first
add minimal skeletal support which only compiles but does not provide
any functionality.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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The RISC-V host will have one guest external interrupt line for each
VS-level IMSICs associated with a HART. The guest external interrupt
lines are per-HART resources and hypervisor can use HGEIE, HGEIP, and
HIE CSRs to manage these guest external interrupt lines.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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The AIA specification introduce per-HART AIA CSRs which primarily
support:
* 64 local interrupts on both RV64 and RV32
* priority for each of the 64 local interrupts
* interrupt filtering for local interrupts
This patch virtualize above mentioned AIA CSRs and also extend
ONE_REG interface to allow user-space save/restore Guest/VM
view of these CSRs.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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To incrementally implement AIA support, we first add minimal skeletal
support which only compiles and detects AIA hardware support at the
boot-time but does not provide any functionality.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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