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linux/arch/riscv/include/asm/kvm_host.h
Palmer Dabbelt 5ee121a393
Merge patch series "riscv: Apply Zawrs when available" 
Andrew Jones <ajones@ventanamicro.com> says:

Zawrs provides two instructions (wrs.nto and wrs.sto), where both are
meant to allow the hart to enter a low-power state while waiting on a
store to a memory location. The instructions also both wait an
implementation-defined "short" duration (unless the implementation
terminates the stall for another reason). The difference is that while
wrs.sto will terminate when the duration elapses, wrs.nto, depending on
configuration, will either just keep waiting or an ILL exception will be
raised. Linux will use wrs.nto, so if platforms have an implementation
which falls in the "just keep waiting" category (which is not expected),
then it should _not_ advertise Zawrs in the hardware description.

Like wfi (and with the same {m,h}status bits to configure it), when
wrs.nto is configured to raise exceptions it's expected that the higher
privilege level will see the instruction was a wait instruction, do
something, and then resume execution following the instruction. For
example, KVM does configure exceptions for wfi (hstatus.VTW=1) and
therefore also for wrs.nto. KVM does this for wfi since it's better to
allow other tasks to be scheduled while a VCPU waits for an interrupt.
For waits such as those where wrs.nto/sto would be used, which are
typically locks, it is also a good idea for KVM to be involved, as it
can attempt to schedule the lock holding VCPU.

This series starts with Christoph's addition of the riscv
smp_cond_load_relaxed function which applies wrs.sto when available.
That patch has been reworked to use wrs.nto and to use the same approach
as Arm for the wait loop, since we can't have arbitrary C code between
the load-reserved and the wrs. Then, hwprobe support is added (since the
instructions are also usable from usermode), and finally KVM is
taught about wrs.nto, allowing guests to see and use the Zawrs
extension.

We still don't have test results from hardware, and it's not possible to
prove that using Zawrs is a win when testing on QEMU, not even when
oversubscribing VCPUs to guests. However, it is possible to use KVM
selftests to force a scenario where we can prove Zawrs does its job and
does it well. [4] is a test which does this and, on my machine, without
Zawrs it takes 16 seconds to complete and with Zawrs it takes 0.25
seconds.

This series is also available here [1]. In order to use QEMU for testing
a build with [2] is needed. In order to enable guests to use Zawrs with
KVM using kvmtool, the branch at [3] may be used.

[1] https://github.com/jones-drew/linux/commits/riscv/zawrs-v3/
[2] https://lore.kernel.org/all/20240312152901.512001-2-ajones@ventanamicro.com/
[3] https://github.com/jones-drew/kvmtool/commits/riscv/zawrs/
[4] cb2beccebc

Link: https://lore.kernel.org/r/20240426100820.14762-8-ajones@ventanamicro.com

* b4-shazam-merge:
  KVM: riscv: selftests: Add Zawrs extension to get-reg-list test
  KVM: riscv: Support guest wrs.nto
  riscv: hwprobe: export Zawrs ISA extension
  riscv: Add Zawrs support for spinlocks
  dt-bindings: riscv: Add Zawrs ISA extension description
  riscv: Provide a definition for 'pause'

Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-12 08:55:29 -07:00

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2019 Western Digital Corporation or its affiliates.
*
* Authors:
* Anup Patel <anup.patel@wdc.com>
*/
#ifndef __RISCV_KVM_HOST_H__
#define __RISCV_KVM_HOST_H__
#include <linux/types.h>
#include <linux/kvm.h>
#include <linux/kvm_types.h>
#include <linux/spinlock.h>
#include <asm/hwcap.h>
#include <asm/kvm_aia.h>
#include <asm/ptrace.h>
#include <asm/kvm_vcpu_fp.h>
#include <asm/kvm_vcpu_insn.h>
#include <asm/kvm_vcpu_sbi.h>
#include <asm/kvm_vcpu_timer.h>
#include <asm/kvm_vcpu_pmu.h>
#define KVM_MAX_VCPUS 1024
#define KVM_HALT_POLL_NS_DEFAULT 500000
#define KVM_VCPU_MAX_FEATURES 0
#define KVM_IRQCHIP_NUM_PINS 1024
#define KVM_REQ_SLEEP \
KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
#define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(1)
#define KVM_REQ_UPDATE_HGATP KVM_ARCH_REQ(2)
#define KVM_REQ_FENCE_I \
KVM_ARCH_REQ_FLAGS(3, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
#define KVM_REQ_HFENCE_GVMA_VMID_ALL KVM_REQ_TLB_FLUSH
#define KVM_REQ_HFENCE_VVMA_ALL \
KVM_ARCH_REQ_FLAGS(4, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
#define KVM_REQ_HFENCE \
KVM_ARCH_REQ_FLAGS(5, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
#define KVM_REQ_STEAL_UPDATE KVM_ARCH_REQ(6)
#define KVM_HEDELEG_DEFAULT (BIT(EXC_INST_MISALIGNED) | \
BIT(EXC_BREAKPOINT) | \
BIT(EXC_SYSCALL) | \
BIT(EXC_INST_PAGE_FAULT) | \
BIT(EXC_LOAD_PAGE_FAULT) | \
BIT(EXC_STORE_PAGE_FAULT))
#define KVM_HIDELEG_DEFAULT (BIT(IRQ_VS_SOFT) | \
BIT(IRQ_VS_TIMER) | \
BIT(IRQ_VS_EXT))
enum kvm_riscv_hfence_type {
KVM_RISCV_HFENCE_UNKNOWN = 0,
KVM_RISCV_HFENCE_GVMA_VMID_GPA,
KVM_RISCV_HFENCE_VVMA_ASID_GVA,
KVM_RISCV_HFENCE_VVMA_ASID_ALL,
KVM_RISCV_HFENCE_VVMA_GVA,
};
struct kvm_riscv_hfence {
enum kvm_riscv_hfence_type type;
unsigned long asid;
unsigned long order;
gpa_t addr;
gpa_t size;
};
#define KVM_RISCV_VCPU_MAX_HFENCE 64
struct kvm_vm_stat {
struct kvm_vm_stat_generic generic;
};
struct kvm_vcpu_stat {
struct kvm_vcpu_stat_generic generic;
u64 ecall_exit_stat;
u64 wfi_exit_stat;
u64 wrs_exit_stat;
u64 mmio_exit_user;
u64 mmio_exit_kernel;
u64 csr_exit_user;
u64 csr_exit_kernel;
u64 signal_exits;
u64 exits;
};
struct kvm_arch_memory_slot {
};
struct kvm_vmid {
/*
* Writes to vmid_version and vmid happen with vmid_lock held
* whereas reads happen without any lock held.
*/
unsigned long vmid_version;
unsigned long vmid;
};
struct kvm_arch {
/* G-stage vmid */
struct kvm_vmid vmid;
/* G-stage page table */
pgd_t *pgd;
phys_addr_t pgd_phys;
/* Guest Timer */
struct kvm_guest_timer timer;
/* AIA Guest/VM context */
struct kvm_aia aia;
};
struct kvm_cpu_trap {
unsigned long sepc;
unsigned long scause;
unsigned long stval;
unsigned long htval;
unsigned long htinst;
};
struct kvm_cpu_context {
unsigned long zero;
unsigned long ra;
unsigned long sp;
unsigned long gp;
unsigned long tp;
unsigned long t0;
unsigned long t1;
unsigned long t2;
unsigned long s0;
unsigned long s1;
unsigned long a0;
unsigned long a1;
unsigned long a2;
unsigned long a3;
unsigned long a4;
unsigned long a5;
unsigned long a6;
unsigned long a7;
unsigned long s2;
unsigned long s3;
unsigned long s4;
unsigned long s5;
unsigned long s6;
unsigned long s7;
unsigned long s8;
unsigned long s9;
unsigned long s10;
unsigned long s11;
unsigned long t3;
unsigned long t4;
unsigned long t5;
unsigned long t6;
unsigned long sepc;
unsigned long sstatus;
unsigned long hstatus;
union __riscv_fp_state fp;
struct __riscv_v_ext_state vector;
};
struct kvm_vcpu_csr {
unsigned long vsstatus;
unsigned long vsie;
unsigned long vstvec;
unsigned long vsscratch;
unsigned long vsepc;
unsigned long vscause;
unsigned long vstval;
unsigned long hvip;
unsigned long vsatp;
unsigned long scounteren;
unsigned long senvcfg;
};
struct kvm_vcpu_config {
u64 henvcfg;
u64 hstateen0;
unsigned long hedeleg;
};
struct kvm_vcpu_smstateen_csr {
unsigned long sstateen0;
};
struct kvm_vcpu_arch {
/* VCPU ran at least once */
bool ran_atleast_once;
/* Last Host CPU on which Guest VCPU exited */
int last_exit_cpu;
/* ISA feature bits (similar to MISA) */
DECLARE_BITMAP(isa, RISCV_ISA_EXT_MAX);
/* Vendor, Arch, and Implementation details */
unsigned long mvendorid;
unsigned long marchid;
unsigned long mimpid;
/* SSCRATCH, STVEC, and SCOUNTEREN of Host */
unsigned long host_sscratch;
unsigned long host_stvec;
unsigned long host_scounteren;
unsigned long host_senvcfg;
unsigned long host_sstateen0;
/* CPU context of Host */
struct kvm_cpu_context host_context;
/* CPU context of Guest VCPU */
struct kvm_cpu_context guest_context;
/* CPU CSR context of Guest VCPU */
struct kvm_vcpu_csr guest_csr;
/* CPU Smstateen CSR context of Guest VCPU */
struct kvm_vcpu_smstateen_csr smstateen_csr;
/* CPU context upon Guest VCPU reset */
struct kvm_cpu_context guest_reset_context;
spinlock_t reset_cntx_lock;
/* CPU CSR context upon Guest VCPU reset */
struct kvm_vcpu_csr guest_reset_csr;
/*
* VCPU interrupts
*
* We have a lockless approach for tracking pending VCPU interrupts
* implemented using atomic bitops. The irqs_pending bitmap represent
* pending interrupts whereas irqs_pending_mask represent bits changed
* in irqs_pending. Our approach is modeled around multiple producer
* and single consumer problem where the consumer is the VCPU itself.
*/
#define KVM_RISCV_VCPU_NR_IRQS 64
DECLARE_BITMAP(irqs_pending, KVM_RISCV_VCPU_NR_IRQS);
DECLARE_BITMAP(irqs_pending_mask, KVM_RISCV_VCPU_NR_IRQS);
/* VCPU Timer */
struct kvm_vcpu_timer timer;
/* HFENCE request queue */
spinlock_t hfence_lock;
unsigned long hfence_head;
unsigned long hfence_tail;
struct kvm_riscv_hfence hfence_queue[KVM_RISCV_VCPU_MAX_HFENCE];
/* MMIO instruction details */
struct kvm_mmio_decode mmio_decode;
/* CSR instruction details */
struct kvm_csr_decode csr_decode;
/* SBI context */
struct kvm_vcpu_sbi_context sbi_context;
/* AIA VCPU context */
struct kvm_vcpu_aia aia_context;
/* Cache pages needed to program page tables with spinlock held */
struct kvm_mmu_memory_cache mmu_page_cache;
/* VCPU power state */
struct kvm_mp_state mp_state;
spinlock_t mp_state_lock;
/* Don't run the VCPU (blocked) */
bool pause;
/* Performance monitoring context */
struct kvm_pmu pmu_context;
/* 'static' configurations which are set only once */
struct kvm_vcpu_config cfg;
/* SBI steal-time accounting */
struct {
gpa_t shmem;
u64 last_steal;
} sta;
};
static inline void kvm_arch_sync_events(struct kvm *kvm) {}
static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
#define KVM_RISCV_GSTAGE_TLB_MIN_ORDER 12
void kvm_riscv_local_hfence_gvma_vmid_gpa(unsigned long vmid,
gpa_t gpa, gpa_t gpsz,
unsigned long order);
void kvm_riscv_local_hfence_gvma_vmid_all(unsigned long vmid);
void kvm_riscv_local_hfence_gvma_gpa(gpa_t gpa, gpa_t gpsz,
unsigned long order);
void kvm_riscv_local_hfence_gvma_all(void);
void kvm_riscv_local_hfence_vvma_asid_gva(unsigned long vmid,
unsigned long asid,
unsigned long gva,
unsigned long gvsz,
unsigned long order);
void kvm_riscv_local_hfence_vvma_asid_all(unsigned long vmid,
unsigned long asid);
void kvm_riscv_local_hfence_vvma_gva(unsigned long vmid,
unsigned long gva, unsigned long gvsz,
unsigned long order);
void kvm_riscv_local_hfence_vvma_all(unsigned long vmid);
void kvm_riscv_local_tlb_sanitize(struct kvm_vcpu *vcpu);
void kvm_riscv_fence_i_process(struct kvm_vcpu *vcpu);
void kvm_riscv_hfence_gvma_vmid_all_process(struct kvm_vcpu *vcpu);
void kvm_riscv_hfence_vvma_all_process(struct kvm_vcpu *vcpu);
void kvm_riscv_hfence_process(struct kvm_vcpu *vcpu);
void kvm_riscv_fence_i(struct kvm *kvm,
unsigned long hbase, unsigned long hmask);
void kvm_riscv_hfence_gvma_vmid_gpa(struct kvm *kvm,
unsigned long hbase, unsigned long hmask,
gpa_t gpa, gpa_t gpsz,
unsigned long order);
void kvm_riscv_hfence_gvma_vmid_all(struct kvm *kvm,
unsigned long hbase, unsigned long hmask);
void kvm_riscv_hfence_vvma_asid_gva(struct kvm *kvm,
unsigned long hbase, unsigned long hmask,
unsigned long gva, unsigned long gvsz,
unsigned long order, unsigned long asid);
void kvm_riscv_hfence_vvma_asid_all(struct kvm *kvm,
unsigned long hbase, unsigned long hmask,
unsigned long asid);
void kvm_riscv_hfence_vvma_gva(struct kvm *kvm,
unsigned long hbase, unsigned long hmask,
unsigned long gva, unsigned long gvsz,
unsigned long order);
void kvm_riscv_hfence_vvma_all(struct kvm *kvm,
unsigned long hbase, unsigned long hmask);
int kvm_riscv_gstage_ioremap(struct kvm *kvm, gpa_t gpa,
phys_addr_t hpa, unsigned long size,
bool writable, bool in_atomic);
void kvm_riscv_gstage_iounmap(struct kvm *kvm, gpa_t gpa,
unsigned long size);
int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
struct kvm_memory_slot *memslot,
gpa_t gpa, unsigned long hva, bool is_write);
int kvm_riscv_gstage_alloc_pgd(struct kvm *kvm);
void kvm_riscv_gstage_free_pgd(struct kvm *kvm);
void kvm_riscv_gstage_update_hgatp(struct kvm_vcpu *vcpu);
void __init kvm_riscv_gstage_mode_detect(void);
unsigned long __init kvm_riscv_gstage_mode(void);
int kvm_riscv_gstage_gpa_bits(void);
void __init kvm_riscv_gstage_vmid_detect(void);
unsigned long kvm_riscv_gstage_vmid_bits(void);
int kvm_riscv_gstage_vmid_init(struct kvm *kvm);
bool kvm_riscv_gstage_vmid_ver_changed(struct kvm_vmid *vmid);
void kvm_riscv_gstage_vmid_update(struct kvm_vcpu *vcpu);
int kvm_riscv_setup_default_irq_routing(struct kvm *kvm, u32 lines);
void __kvm_riscv_unpriv_trap(void);
unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
bool read_insn,
unsigned long guest_addr,
struct kvm_cpu_trap *trap);
void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
struct kvm_cpu_trap *trap);
int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
struct kvm_cpu_trap *trap);
void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch);
void kvm_riscv_vcpu_setup_isa(struct kvm_vcpu *vcpu);
unsigned long kvm_riscv_vcpu_num_regs(struct kvm_vcpu *vcpu);
int kvm_riscv_vcpu_copy_reg_indices(struct kvm_vcpu *vcpu,
u64 __user *uindices);
int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg);
int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg);
int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu);
bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, u64 mask);
void __kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
void __kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
bool kvm_riscv_vcpu_stopped(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu);
#endif /* __RISCV_KVM_HOST_H__ */
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