- 根目录:
- arch
- powerpc
- kvm
- book3s_hv_rm_xics.c
/*
* Copyright 2012 Michael Ellerman, IBM Corporation.
* Copyright 2012 Benjamin Herrenschmidt, IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <linux/err.h>
#include <asm/kvm_book3s.h>
#include <asm/kvm_ppc.h>
#include <asm/hvcall.h>
#include <asm/xics.h>
#include <asm/debug.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include "book3s_xics.h"
#define DEBUG_PASSUP
static void icp_rm_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
u32 new_irq);
/* -- ICS routines -- */
static void ics_rm_check_resend(struct kvmppc_xics *xics,
struct kvmppc_ics *ics, struct kvmppc_icp *icp)
{
int i;
arch_spin_lock(&ics->lock);
for (i = 0; i < KVMPPC_XICS_IRQ_PER_ICS; i++) {
struct ics_irq_state *state = &ics->irq_state[i];
if (!state->resend)
continue;
arch_spin_unlock(&ics->lock);
icp_rm_deliver_irq(xics, icp, state->number);
arch_spin_lock(&ics->lock);
}
arch_spin_unlock(&ics->lock);
}
/* -- ICP routines -- */
static void icp_rm_set_vcpu_irq(struct kvm_vcpu *vcpu,
struct kvm_vcpu *this_vcpu)
{
struct kvmppc_icp *this_icp = this_vcpu->arch.icp;
int cpu;
/* Mark the target VCPU as having an interrupt pending */
vcpu->stat.queue_intr++;
set_bit(BOOK3S_IRQPRIO_EXTERNAL_LEVEL, &vcpu->arch.pending_exceptions);
/* Kick self ? Just set MER and return */
if (vcpu == this_vcpu) {
mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_MER);
return;
}
/* Check if the core is loaded, if not, too hard */
cpu = vcpu->arch.thread_cpu;
if (cpu < 0 || cpu >= nr_cpu_ids) {
this_icp->rm_action |= XICS_RM_KICK_VCPU;
this_icp->rm_kick_target = vcpu;
return;
}
smp_mb();
kvmhv_rm_send_ipi(cpu);
}
static void icp_rm_clr_vcpu_irq(struct kvm_vcpu *vcpu)
{
/* Note: Only called on self ! */
clear_bit(BOOK3S_IRQPRIO_EXTERNAL_LEVEL,
&vcpu->arch.pending_exceptions);
mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~LPCR_MER);
}
static inline bool icp_rm_try_update(struct kvmppc_icp *icp,
union kvmppc_icp_state old,
union kvmppc_icp_state new)
{
struct kvm_vcpu *this_vcpu = local_paca->kvm_hstate.kvm_vcpu;
bool success;
/* Calculate new output value */
new.out_ee = (new.xisr && (new.pending_pri < new.cppr));
/* Attempt atomic update */
success = cmpxchg64(&icp->state.raw, old.raw, new.raw) == old.raw;
if (!success)
goto bail;
/*
* Check for output state update
*
* Note that this is racy since another processor could be updating
* the state already. This is why we never clear the interrupt output
* here, we only ever set it. The clear only happens prior to doing
* an update and only by the processor itself. Currently we do it
* in Accept (H_XIRR) and Up_Cppr (H_XPPR).
*
* We also do not try to figure out whether the EE state has changed,
* we unconditionally set it if the new state calls for it. The reason
* for that is that we opportunistically remove the pending interrupt
* flag when raising CPPR, so we need to set it back here if an
* interrupt is still pending.
*/
if (new.out_ee)
icp_rm_set_vcpu_irq(icp->vcpu, this_vcpu);
/* Expose the state change for debug purposes */
this_vcpu->arch.icp->rm_dbgstate = new;
this_vcpu->arch.icp->rm_dbgtgt = icp->vcpu;
bail:
return success;
}
static inline int check_too_hard(struct kvmppc_xics *xics,
struct kvmppc_icp *icp)
{
return (xics->real_mode_dbg || icp->rm_action) ? H_TOO_HARD : H_SUCCESS;
}
static void icp_rm_check_resend(struct kvmppc_xics *xics,
struct kvmppc_icp *icp)
{
u32 icsid;
/* Order this load with the test for need_resend in the caller */
smp_rmb();
for_each_set_bit(icsid, icp->resend_map, xics->max_icsid + 1) {
struct kvmppc_ics *ics = xics->ics[icsid];
if (!test_and_clear_bit(icsid, icp->resend_map))
continue;
if (!ics)
continue;
ics_rm_check_resend(xics, ics, icp);
}
}
static bool icp_rm_try_to_deliver(struct kvmppc_icp *icp, u32 irq, u8 priority,
u32 *reject)
{
union kvmppc_icp_state old_state, new_state;
bool success;
do {
old_state = new_state = READ_ONCE(icp->state);
*reject = 0;
/* See if we can deliver */
success = new_state.cppr > priority &&
new_state.mfrr > priority &&
new_state.pending_pri > priority;
/*
* If we can, check for a rejection and perform the
* delivery
*/
if (success) {
*reject = new_state.xisr;
new_state.xisr = irq;
new_state.pending_pri = priority;
} else {
/*
* If we failed to deliver we set need_resend
* so a subsequent CPPR state change causes us
* to try a new delivery.
*/
new_state.need_resend = true;
}
} while (!icp_rm_try_update(icp, old_state, new_state));
return success;
}
static void icp_rm_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
u32 new_irq)
{
struct ics_irq_state *state;
struct kvmppc_ics *ics;
u32 reject;
u16 src;
/*
* This is used both for initial delivery of an interrupt and
* for subsequent rejection.
*
* Rejection can be racy vs. resends. We have evaluated the
* rejection in an atomic ICP transaction which is now complete,
* so potentially the ICP can already accept the interrupt again.
*
* So we need to retry the delivery. Essentially the reject path
* boils down to a failed delivery. Always.
*
* Now the interrupt could also have moved to a different target,
* thus we may need to re-do the ICP lookup as well
*/
again:
/* Get the ICS state and lock it */
ics = kvmppc_xics_find_ics(xics, new_irq, &src);
if (!ics) {
/* Unsafe increment, but this does not need to be accurate */
xics->err_noics++;
return;
}
state = &ics->irq_state[src];
/* Get a lock on the ICS */
arch_spin_lock(&ics->lock);
/* Get our server */
if (!icp || state->server != icp->server_num) {
icp = kvmppc_xics_find_server(xics->kvm, state->server);
if (!icp) {
/* Unsafe increment again*/
xics->err_noicp++;
goto out;
}
}
/* Clear the resend bit of that interrupt */
state->resend = 0;
/*
* If masked, bail out
*
* Note: PAPR doesn't mention anything about masked pending
* when doing a resend, only when doing a delivery.
*
* However that would have the effect of losing a masked
* interrupt that was rejected and isn't consistent with
* the whole masked_pending business which is about not
* losing interrupts that occur while masked.
*
* I don't differentiate normal deliveries and resends, this
* implementation will differ from PAPR and not lose such
* interrupts.
*/
if (state->priority == MASKED) {
state->masked_pending = 1;
goto out;
}
/*
* Try the delivery, this will set the need_resend flag
* in the ICP as part of the atomic transaction if the
* delivery is not possible.
*
* Note that if successful, the new delivery might have itself
* rejected an interrupt that was "delivered" before we took the
* ics spin lock.
*
* In this case we do the whole sequence all over again for the
* new guy. We cannot assume that the rejected interrupt is less
* favored than the new one, and thus doesn't need to be delivered,
* because by the time we exit icp_rm_try_to_deliver() the target
* processor may well have already consumed & completed it, and thus
* the rejected interrupt might actually be already acceptable.
*/
if (icp_rm_try_to_deliver(icp, new_irq, state->priority, &reject)) {
/*
* Delivery was successful, did we reject somebody else ?
*/
if (reject && reject != XICS_IPI) {
arch_spin_unlock(&ics->lock);
new_irq = reject;
goto again;
}
} else {
/*
* We failed to deliver the interrupt we need to set the
* resend map bit and mark the ICS state as needing a resend
*/
set_bit(ics->icsid, icp->resend_map);
state->resend = 1;
/*
* If the need_resend flag got cleared in the ICP some time
* between icp_rm_try_to_deliver() atomic update and now, then
* we know it might have missed the resend_map bit. So we
* retry
*/
smp_mb();
if (!icp->state.need_resend) {
arch_spin_unlock(&ics->lock);
goto again;
}
}
out:
arch_spin_unlock(&ics->lock);
}
static void icp_rm_down_cppr(struct kvmppc_xics *xics, struct kvmppc_icp *icp,
u8 new_cppr)
{
union kvmppc_icp_state old_state, new_state;
bool resend;
/*
* This handles several related states in one operation:
*
* ICP State: Down_CPPR
*
* Load CPPR with new value and if the XISR is 0
* then check for resends:
*
* ICP State: Resend
*
* If MFRR is more favored than CPPR, check for IPIs
* and notify ICS of a potential resend. This is done
* asynchronously (when used in real mode, we will have
* to exit here).
*
* We do not handle the complete Check_IPI as documented
* here. In the PAPR, this state will be used for both
* Set_MFRR and Down_CPPR. However, we know that we aren't
* changing the MFRR state here so we don't need to handle
* the case of an MFRR causing a reject of a pending irq,
* this will have been handled when the MFRR was set in the
* first place.
*
* Thus we don't have to handle rejects, only resends.
*
* When implementing real mode for HV KVM, resend will lead to
* a H_TOO_HARD return and the whole transaction will be handled
* in virtual mode.
*/
do {
old_state = new_state = READ_ONCE(icp->state);
/* Down_CPPR */
new_state.cppr = new_cppr;
/*
* Cut down Resend / Check_IPI / IPI
*
* The logic is that we cannot have a pending interrupt
* trumped by an IPI at this point (see above), so we
* know that either the pending interrupt is already an
* IPI (in which case we don't care to override it) or
* it's either more favored than us or non existent
*/
if (new_state.mfrr < new_cppr &&
new_state.mfrr <= new_state.pending_pri) {
new_state.pending_pri = new_state.mfrr;
new_state.xisr = XICS_IPI;
}
/* Latch/clear resend bit */
resend = new_state.need_resend;
new_state.need_resend = 0;
} while (!icp_rm_try_update(icp, old_state, new_state));
/*
* Now handle resend checks. Those are asynchronous to the ICP
* state update in HW (ie bus transactions) so we can handle them
* separately here as well.
*/
if (resend) {
icp->n_check_resend++;
icp_rm_check_resend(xics, icp);
}
}
unsigned long kvmppc_rm_h_xirr(struct kvm_vcpu *vcpu)
{
union kvmppc_icp_state old_state, new_state;
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
u32 xirr;
if (!xics || !xics->real_mode)
return H_TOO_HARD;
/* First clear the interrupt */
icp_rm_clr_vcpu_irq(icp->vcpu);
/*
* ICP State: Accept_Interrupt
*
* Return the pending interrupt (if any) along with the
* current CPPR, then clear the XISR & set CPPR to the
* pending priority
*/
do {
old_state = new_state = READ_ONCE(icp->state);
xirr = old_state.xisr | (((u32)old_state.cppr) << 24);
if (!old_state.xisr)
break;
new_state.cppr = new_state.pending_pri;
new_state.pending_pri = 0xff;
new_state.xisr = 0;
} while (!icp_rm_try_update(icp, old_state, new_state));
/* Return the result in GPR4 */
vcpu->arch.gpr[4] = xirr;
return check_too_hard(xics, icp);
}
int kvmppc_rm_h_ipi(struct kvm_vcpu *vcpu, unsigned long server,
unsigned long mfrr)
{
union kvmppc_icp_state old_state, new_state;
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp, *this_icp = vcpu->arch.icp;
u32 reject;
bool resend;
bool local;
if (!xics || !xics->real_mode)
return H_TOO_HARD;
local = this_icp->server_num == server;
if (local)
icp = this_icp;
else
icp = kvmppc_xics_find_server(vcpu->kvm, server);
if (!icp)
return H_PARAMETER;
/*
* ICP state: Set_MFRR
*
* If the CPPR is more favored than the new MFRR, then
* nothing needs to be done as there can be no XISR to
* reject.
*
* ICP state: Check_IPI
*
* If the CPPR is less favored, then we might be replacing
* an interrupt, and thus need to possibly reject it.
*
* ICP State: IPI
*
* Besides rejecting any pending interrupts, we also
* update XISR and pending_pri to mark IPI as pending.
*
* PAPR does not describe this state, but if the MFRR is being
* made less favored than its earlier value, there might be
* a previously-rejected interrupt needing to be resent.
* Ideally, we would want to resend only if
* prio(pending_interrupt) < mfrr &&
* prio(pending_interrupt) < cppr
* where pending interrupt is the one that was rejected. But
* we don't have that state, so we simply trigger a resend
* whenever the MFRR is made less favored.
*/
do {
old_state = new_state = READ_ONCE(icp->state);
/* Set_MFRR */
new_state.mfrr = mfrr;
/* Check_IPI */
reject = 0;
resend = false;
if (mfrr < new_state.cppr) {
/* Reject a pending interrupt if not an IPI */
if (mfrr <= new_state.pending_pri) {
reject = new_state.xisr;
new_state.pending_pri = mfrr;
new_state.xisr = XICS_IPI;
}
}
if (mfrr > old_state.mfrr) {
resend = new_state.need_resend;
new_state.need_resend = 0;
}
} while (!icp_rm_try_update(icp, old_state, new_state));
/* Handle reject in real mode */
if (reject && reject != XICS_IPI) {
this_icp->n_reject++;
icp_rm_deliver_irq(xics, icp, reject);
}
/* Handle resends in real mode */
if (resend) {
this_icp->n_check_resend++;
icp_rm_check_resend(xics, icp);
}
return check_too_hard(xics, this_icp);
}
int kvmppc_rm_h_cppr(struct kvm_vcpu *vcpu, unsigned long cppr)
{
union kvmppc_icp_state old_state, new_state;
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
u32 reject;
if (!xics || !xics->real_mode)
return H_TOO_HARD;
/*
* ICP State: Set_CPPR
*
* We can safely compare the new value with the current
* value outside of the transaction as the CPPR is only
* ever changed by the processor on itself
*/
if (cppr > icp->state.cppr) {
icp_rm_down_cppr(xics, icp, cppr);
goto bail;
} else if (cppr == icp->state.cppr)
return H_SUCCESS;
/*
* ICP State: Up_CPPR
*
* The processor is raising its priority, this can result
* in a rejection of a pending interrupt:
*
* ICP State: Reject_Current
*
* We can remove EE from the current processor, the update
* transaction will set it again if needed
*/
icp_rm_clr_vcpu_irq(icp->vcpu);
do {
old_state = new_state = READ_ONCE(icp->state);
reject = 0;
new_state.cppr = cppr;
if (cppr <= new_state.pending_pri) {
reject = new_state.xisr;
new_state.xisr = 0;
new_state.pending_pri = 0xff;
}
} while (!icp_rm_try_update(icp, old_state, new_state));
/*
* Check for rejects. They are handled by doing a new delivery
* attempt (see comments in icp_rm_deliver_irq).
*/
if (reject && reject != XICS_IPI) {
icp->n_reject++;
icp_rm_deliver_irq(xics, icp, reject);
}
bail:
return check_too_hard(xics, icp);
}
int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu, unsigned long xirr)
{
struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
struct kvmppc_icp *icp = vcpu->arch.icp;
struct kvmppc_ics *ics;
struct ics_irq_state *state;
u32 irq = xirr & 0x00ffffff;
u16 src;
if (!xics || !xics->real_mode)
return H_TOO_HARD;
/*
* ICP State: EOI
*
* Note: If EOI is incorrectly used by SW to lower the CPPR
* value (ie more favored), we do not check for rejection of
* a pending interrupt, this is a SW error and PAPR sepcifies
* that we don't have to deal with it.
*
* The sending of an EOI to the ICS is handled after the
* CPPR update
*
* ICP State: Down_CPPR which we handle
* in a separate function as it's shared with H_CPPR.
*/
icp_rm_down_cppr(xics, icp, xirr >> 24);
/* IPIs have no EOI */
if (irq == XICS_IPI)
goto bail;
/*
* EOI handling: If the interrupt is still asserted, we need to
* resend it. We can take a lockless "peek" at the ICS state here.
*
* "Message" interrupts will never have "asserted" set
*/
ics = kvmppc_xics_find_ics(xics, irq, &src);
if (!ics)
goto bail;
state = &ics->irq_state[src];
/* Still asserted, resend it */
if (state->asserted) {
icp->n_reject++;
icp_rm_deliver_irq(xics, icp, irq);
}
if (!hlist_empty(&vcpu->kvm->irq_ack_notifier_list)) {
icp->rm_action |= XICS_RM_NOTIFY_EOI;
icp->rm_eoied_irq = irq;
}
bail:
return check_too_hard(xics, icp);
}