RISC-V: KVM: Redirect AMO load/store misaligned traps to guest

The M-mode redirects an unhandled misaligned trap back
to S-mode when not delegating it to VS-mode(hedeleg).
However, KVM running in HS-mode terminates the VS-mode
software when back from M-mode.
The KVM should redirect the trap back to VS-mode, and
let VS-mode trap handler decide the next step.
Here is a way to handle misaligned traps in KVM,
not only directing them to VS-mode or terminate it.

Signed-off-by: wchen <waylingII@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Anup Patel <anup@brainfault.org>

RISC-V: KVM: Redirect illegal instruction traps to guest

The M-mode redirects an unhandled illegal instruction trap back
to S-mode. However, KVM running in HS-mode terminates the VS-mode
software when it receives illegal instruction trap. Instead, KVM
should redirect the illegal instruction trap back to VS-mode, and
let VS-mode trap handler decide the next step. This futher allows
guest kernel to implement on-demand enabling of vector extension
for a guest user space process upon first-use.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
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>

RISC-V: KVM: Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()

The kvm_riscv_vcpu_trap_redirect() should set guest privilege mode
to supervisor mode because guest traps/interrupts are always handled
in virtual supervisor mode.

Fixes: 9f7013265112 ("RISC-V: KVM: Handle MMIO exits for VCPU")
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>

riscv: KVM: Apply insn-def to hlv encodings

Introduce hlv instruction encodings and apply them to KVM's use.
We're careful not to introduce hlv.d to 32-bit builds. Indeed,
we ensure the build fails if someone tries to use it.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Anup Patel <anup@brainfault.org>

RISC-V: KVM: Factor-out instruction emulation into separate sources

The instruction and CSR emulation for VCPU is going to grow over time
due to upcoming AIA, PMU, Nested and other virtualization features.

Let us factor-out VCPU instruction emulation from vcpu_exit.c to a
separate source dedicated for this purpose.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

RISC-V: KVM: Fix variable spelling mistake

There is a spelling mistake in mmu.c and vcpu_exit.c. Fix it.

Signed-off-by: Zhang Jiaming <jiaming@nfschina.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

RISC-V: KVM: Use G-stage name for hypervisor page table

The two-stage address translation defined by the RISC-V privileged
specification defines: VS-stage (guest virtual address to guest
physical address) programmed by the Guest OS and G-stage (guest
physical addree to host physical address) programmed by the
hypervisor.

To align with above terminology, we replace "stage2" with "gstage"
and "Stage2" with "G-stage" name everywhere in KVM RISC-V sources.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

KVM: Add helpers to wrap vcpu->srcu_idx and yell if it's abused

Add wrappers to acquire/release KVM's SRCU lock when stashing the index
in vcpu->src_idx, along with rudimentary detection of illegal usage,
e.g. re-acquiring SRCU and thus overwriting vcpu->src_idx. Because the
SRCU index is (currently) either 0 or 1, illegal nesting bugs can go
unnoticed for quite some time and only cause problems when the nested
lock happens to get a different index.

Wrap the WARNs in PROVE_RCU=y, and make them ONCE, otherwise KVM will
likely yell so loudly that it will bring the kernel to its knees.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20220415004343.2203171-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: RISC-V: Use kvm_vcpu.srcu_idx, drop RISC-V's unnecessary copy

Use the generic kvm_vcpu's srcu_idx instead of using an indentical field
in RISC-V's version of kvm_vcpu_arch. Generic KVM very intentionally
does not touch vcpu->srcu_idx, i.e. there's zero chance of running afoul
of common code.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220415004343.2203171-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

RISC-V: KVM: Add common kvm_riscv_vcpu_wfi() function

The wait for interrupt (WFI) instruction emulation can share the VCPU
halt logic with SBI HSM suspend emulation so this patch adds a common
kvm_riscv_vcpu_wfi() function for this purpose.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt()

Rename kvm_vcpu_block() to kvm_vcpu_halt() in preparation for splitting
the actual "block" sequences into a separate helper (to be named
kvm_vcpu_block()). x86 will use the standalone block-only path to handle
non-halt cases where the vCPU is not runnable.

Rename block_ns to halt_ns to match the new function name.

No functional change intended.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

RISC-V: KVM: remove unneeded semicolon

Elimate the following coccinelle check warning:
./arch/riscv/kvm/vcpu_sbi.c:169:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu_exit.c:397:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu_exit.c:687:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu_exit.c:645:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu.c:247:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu.c:284:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu_timer.c:123:2-3: Unneeded semicolon
./arch/riscv/kvm/vcpu_timer.c:170:2-3: Unneeded semicolon

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ran jianping <ran.jianping@zte.com.cn>
Signed-off-by: Anup Patel <anup.patel@wdc.com>

RISC-V: KVM: Add SBI v0.1 support

The KVM host kernel is running in HS-mode needs so we need to handle
the SBI calls coming from guest kernel running in VS-mode.

This patch adds SBI v0.1 support in KVM RISC-V. Almost all SBI v0.1
calls are implemented in KVM kernel module except GETCHAR and PUTCHART
calls which are forwarded to user space because these calls cannot be
implemented in kernel space. In future, when we implement SBI v0.2 for
Guest, we will forward SBI v0.2 experimental and vendor extension calls
to user space.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

RISC-V: KVM: Handle WFI exits for VCPU

We get illegal instruction trap whenever Guest/VM executes WFI
instruction.

This patch handles WFI trap by blocking the trapped VCPU using
kvm_vcpu_block() API. The blocked VCPU will be automatically
resumed whenever a VCPU interrupt is injected from user-space
or from in-kernel IRQCHIP emulation.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

RISC-V: KVM: Handle MMIO exits for VCPU

We will get stage2 page faults whenever Guest/VM access SW emulated
MMIO device or unmapped Guest RAM.

This patch implements MMIO read/write emulation by extracting MMIO
details from the trapped load/store instruction and forwarding the
MMIO read/write to user-space. The actual MMIO emulation will happen
in user-space and KVM kernel module will only take care of register
updates before resuming the trapped VCPU.

The handling for stage2 page faults for unmapped Guest RAM will be
implemeted by a separate patch later.

[jiangyifei: ioeventfd and in-kernel mmio device support]
Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

RISC-V: Add initial skeletal KVM support

This patch adds initial skeletal KVM RISC-V support which has:
1. A simple implementation of arch specific VM functions
except kvm_vm_ioctl_get_dirty_log() which will implemeted
in-future as part of stage2 page loging.
2. Stubs of required arch specific VCPU functions except
kvm_arch_vcpu_ioctl_run() which is semi-complete and
extended by subsequent patches.
3. Stubs for required arch specific stage2 MMU functions.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>