Commit cce69aff authored by Anup Patel's avatar Anup Patel Committed by Anup Patel

RISC-V: KVM: Implement VCPU interrupts and requests handling

This patch implements VCPU interrupts and requests which are both
asynchronous events.

The VCPU interrupts can be set/unset using KVM_INTERRUPT ioctl from
user-space. In future, the in-kernel IRQCHIP emulation will use
kvm_riscv_vcpu_set_interrupt() and kvm_riscv_vcpu_unset_interrupt()
functions to set/unset VCPU interrupts.

Important VCPU requests implemented by this patch are:
KVM_REQ_SLEEP       - set whenever VCPU itself goes to sleep state
KVM_REQ_VCPU_RESET  - set whenever VCPU reset is requested

The WFI trap-n-emulate (added later) will use KVM_REQ_SLEEP request
and kvm_riscv_vcpu_has_interrupt() function.

The KVM_REQ_VCPU_RESET request will be used by SBI emulation (added
later) to power-up a VCPU in power-off state. The user-space can use
the GET_MPSTATE/SET_MPSTATE ioctls to get/set power state of a VCPU.
Signed-off-by: default avatarAnup Patel <anup.patel@wdc.com>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarAlexander Graf <graf@amazon.com>
Acked-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent a33c72fa
......@@ -127,6 +127,21 @@ struct kvm_vcpu_arch {
/* 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.
*/
unsigned long irqs_pending;
unsigned long irqs_pending_mask;
/* VCPU power-off state */
bool power_off;
/* Don't run the VCPU (blocked) */
bool pause;
......@@ -150,4 +165,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
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, unsigned long mask);
void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
#endif /* __RISCV_KVM_HOST_H__ */
......@@ -18,6 +18,9 @@
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
#define KVM_INTERRUPT_SET -1U
#define KVM_INTERRUPT_UNSET -2U
/* for KVM_GET_REGS and KVM_SET_REGS */
struct kvm_regs {
};
......
......@@ -11,6 +11,7 @@
#include <linux/err.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
#include <linux/sched/signal.h>
......@@ -57,6 +58,9 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
memcpy(csr, reset_csr, sizeof(*csr));
memcpy(cntx, reset_cntx, sizeof(*cntx));
WRITE_ONCE(vcpu->arch.irqs_pending, 0);
WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
}
int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
......@@ -100,8 +104,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
{
/* TODO: */
return 0;
return kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER);
}
void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
......@@ -114,20 +117,18 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
{
/* TODO: */
return 0;
return (kvm_riscv_vcpu_has_interrupts(vcpu, -1UL) &&
!vcpu->arch.power_off && !vcpu->arch.pause);
}
int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
{
/* TODO: */
return 0;
return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
}
bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
{
/* TODO: */
return false;
return (vcpu->arch.guest_context.sstatus & SR_SPP) ? true : false;
}
vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
......@@ -138,7 +139,21 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
long kvm_arch_vcpu_async_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
/* TODO; */
struct kvm_vcpu *vcpu = filp->private_data;
void __user *argp = (void __user *)arg;
if (ioctl == KVM_INTERRUPT) {
struct kvm_interrupt irq;
if (copy_from_user(&irq, argp, sizeof(irq)))
return -EFAULT;
if (irq.irq == KVM_INTERRUPT_SET)
return kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_VS_EXT);
else
return kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_EXT);
}
return -ENOIOCTLCMD;
}
......@@ -187,18 +202,123 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
return -EINVAL;
}
void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
unsigned long mask, val;
if (READ_ONCE(vcpu->arch.irqs_pending_mask)) {
mask = xchg_acquire(&vcpu->arch.irqs_pending_mask, 0);
val = READ_ONCE(vcpu->arch.irqs_pending) & mask;
csr->hvip &= ~mask;
csr->hvip |= val;
}
}
void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
{
unsigned long hvip;
struct kvm_vcpu_arch *v = &vcpu->arch;
struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
/* Read current HVIP and VSIE CSRs */
csr->vsie = csr_read(CSR_VSIE);
/* Sync-up HVIP.VSSIP bit changes does by Guest */
hvip = csr_read(CSR_HVIP);
if ((csr->hvip ^ hvip) & (1UL << IRQ_VS_SOFT)) {
if (hvip & (1UL << IRQ_VS_SOFT)) {
if (!test_and_set_bit(IRQ_VS_SOFT,
&v->irqs_pending_mask))
set_bit(IRQ_VS_SOFT, &v->irqs_pending);
} else {
if (!test_and_set_bit(IRQ_VS_SOFT,
&v->irqs_pending_mask))
clear_bit(IRQ_VS_SOFT, &v->irqs_pending);
}
}
}
int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq)
{
if (irq != IRQ_VS_SOFT &&
irq != IRQ_VS_TIMER &&
irq != IRQ_VS_EXT)
return -EINVAL;
set_bit(irq, &vcpu->arch.irqs_pending);
smp_mb__before_atomic();
set_bit(irq, &vcpu->arch.irqs_pending_mask);
kvm_vcpu_kick(vcpu);
return 0;
}
int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq)
{
if (irq != IRQ_VS_SOFT &&
irq != IRQ_VS_TIMER &&
irq != IRQ_VS_EXT)
return -EINVAL;
clear_bit(irq, &vcpu->arch.irqs_pending);
smp_mb__before_atomic();
set_bit(irq, &vcpu->arch.irqs_pending_mask);
return 0;
}
bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask)
{
unsigned long ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK)
<< VSIP_TO_HVIP_SHIFT) & mask;
return (READ_ONCE(vcpu->arch.irqs_pending) & ie) ? true : false;
}
void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu)
{
vcpu->arch.power_off = true;
kvm_make_request(KVM_REQ_SLEEP, vcpu);
kvm_vcpu_kick(vcpu);
}
void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu)
{
vcpu->arch.power_off = false;
kvm_vcpu_wake_up(vcpu);
}
int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
/* TODO: */
if (vcpu->arch.power_off)
mp_state->mp_state = KVM_MP_STATE_STOPPED;
else
mp_state->mp_state = KVM_MP_STATE_RUNNABLE;
return 0;
}
int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
/* TODO: */
return 0;
int ret = 0;
switch (mp_state->mp_state) {
case KVM_MP_STATE_RUNNABLE:
vcpu->arch.power_off = false;
break;
case KVM_MP_STATE_STOPPED:
kvm_riscv_vcpu_power_off(vcpu);
break;
default:
ret = -EINVAL;
}
return ret;
}
int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
......@@ -222,7 +342,33 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
{
/* TODO: */
struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
if (kvm_request_pending(vcpu)) {
if (kvm_check_request(KVM_REQ_SLEEP, vcpu)) {
rcuwait_wait_event(wait,
(!vcpu->arch.power_off) && (!vcpu->arch.pause),
TASK_INTERRUPTIBLE);
if (vcpu->arch.power_off || vcpu->arch.pause) {
/*
* Awaken to handle a signal, request to
* sleep again later.
*/
kvm_make_request(KVM_REQ_SLEEP, vcpu);
}
}
if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
kvm_riscv_reset_vcpu(vcpu);
}
}
static void kvm_riscv_update_hvip(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
csr_write(CSR_HVIP, csr->hvip);
}
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
......@@ -286,6 +432,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
smp_mb__after_srcu_read_unlock();
/*
* We might have got VCPU interrupts updated asynchronously
* so update it in HW.
*/
kvm_riscv_vcpu_flush_interrupts(vcpu);
/* Update HVIP CSR for current CPU */
kvm_riscv_update_hvip(vcpu);
if (ret <= 0 ||
kvm_request_pending(vcpu)) {
vcpu->mode = OUTSIDE_GUEST_MODE;
......@@ -313,6 +468,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
trap.htval = csr_read(CSR_HTVAL);
trap.htinst = csr_read(CSR_HTINST);
/* Syncup interrupts state with HW */
kvm_riscv_vcpu_sync_interrupts(vcpu);
/*
* We may have taken a host interrupt in VS/VU-mode (i.e.
* while executing the guest). This interrupt is still
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment