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KVM: PPC: Use get/set for to_svcpu to help preemption
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When running the 64-bit Book3s PR code without CONFIG_PREEMPT_NONE, we were
doing a few things wrong, most notably access to PACA fields without making
sure that the pointers stay stable accross the access (preempt_disable()).

This patch moves to_svcpu towards a get/put model which allows us to disable
preemption while accessing the shadow vcpu fields in the PACA. That way we
can run preemptible and everyone's happy!

Reported-by: Jörg Sommer <joerg@alea.gnuu.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
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Alexander Graf authored and Avi Kivity committed Mar 5, 2012
1 parent d33ad32 commit 468a12c
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Showing 8 changed files with 181 additions and 71 deletions.
76 changes: 59 additions & 17 deletions arch/powerpc/include/asm/kvm_book3s.h
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Original file line number Diff line number Diff line change
Expand Up @@ -183,88 +183,130 @@ static inline void kvmppc_update_int_pending(struct kvm_vcpu *vcpu,
static inline void kvmppc_set_gpr(struct kvm_vcpu *vcpu, int num, ulong val)
{
if ( num < 14 ) {
to_svcpu(vcpu)->gpr[num] = val;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
svcpu->gpr[num] = val;
svcpu_put(svcpu);
to_book3s(vcpu)->shadow_vcpu->gpr[num] = val;
} else
vcpu->arch.gpr[num] = val;
}

static inline ulong kvmppc_get_gpr(struct kvm_vcpu *vcpu, int num)
{
if ( num < 14 )
return to_svcpu(vcpu)->gpr[num];
else
if ( num < 14 ) {
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
ulong r = svcpu->gpr[num];
svcpu_put(svcpu);
return r;
} else
return vcpu->arch.gpr[num];
}

static inline void kvmppc_set_cr(struct kvm_vcpu *vcpu, u32 val)
{
to_svcpu(vcpu)->cr = val;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
svcpu->cr = val;
svcpu_put(svcpu);
to_book3s(vcpu)->shadow_vcpu->cr = val;
}

static inline u32 kvmppc_get_cr(struct kvm_vcpu *vcpu)
{
return to_svcpu(vcpu)->cr;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
u32 r;
r = svcpu->cr;
svcpu_put(svcpu);
return r;
}

static inline void kvmppc_set_xer(struct kvm_vcpu *vcpu, u32 val)
{
to_svcpu(vcpu)->xer = val;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
svcpu->xer = val;
to_book3s(vcpu)->shadow_vcpu->xer = val;
svcpu_put(svcpu);
}

static inline u32 kvmppc_get_xer(struct kvm_vcpu *vcpu)
{
return to_svcpu(vcpu)->xer;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
u32 r;
r = svcpu->xer;
svcpu_put(svcpu);
return r;
}

static inline void kvmppc_set_ctr(struct kvm_vcpu *vcpu, ulong val)
{
to_svcpu(vcpu)->ctr = val;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
svcpu->ctr = val;
svcpu_put(svcpu);
}

static inline ulong kvmppc_get_ctr(struct kvm_vcpu *vcpu)
{
return to_svcpu(vcpu)->ctr;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
ulong r;
r = svcpu->ctr;
svcpu_put(svcpu);
return r;
}

static inline void kvmppc_set_lr(struct kvm_vcpu *vcpu, ulong val)
{
to_svcpu(vcpu)->lr = val;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
svcpu->lr = val;
svcpu_put(svcpu);
}

static inline ulong kvmppc_get_lr(struct kvm_vcpu *vcpu)
{
return to_svcpu(vcpu)->lr;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
ulong r;
r = svcpu->lr;
svcpu_put(svcpu);
return r;
}

static inline void kvmppc_set_pc(struct kvm_vcpu *vcpu, ulong val)
{
to_svcpu(vcpu)->pc = val;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
svcpu->pc = val;
svcpu_put(svcpu);
}

static inline ulong kvmppc_get_pc(struct kvm_vcpu *vcpu)
{
return to_svcpu(vcpu)->pc;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
ulong r;
r = svcpu->pc;
svcpu_put(svcpu);
return r;
}

static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu)
{
ulong pc = kvmppc_get_pc(vcpu);
struct kvmppc_book3s_shadow_vcpu *svcpu = to_svcpu(vcpu);
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
u32 r;

/* Load the instruction manually if it failed to do so in the
* exit path */
if (svcpu->last_inst == KVM_INST_FETCH_FAILED)
kvmppc_ld(vcpu, &pc, sizeof(u32), &svcpu->last_inst, false);

return svcpu->last_inst;
r = svcpu->last_inst;
svcpu_put(svcpu);
return r;
}

static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu)
{
return to_svcpu(vcpu)->fault_dar;
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
ulong r;
r = svcpu->fault_dar;
svcpu_put(svcpu);
return r;
}

static inline bool kvmppc_critical_section(struct kvm_vcpu *vcpu)
Expand Down
6 changes: 5 additions & 1 deletion arch/powerpc/include/asm/kvm_book3s_32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,11 +20,15 @@
#ifndef __ASM_KVM_BOOK3S_32_H__
#define __ASM_KVM_BOOK3S_32_H__

static inline struct kvmppc_book3s_shadow_vcpu *to_svcpu(struct kvm_vcpu *vcpu)
static inline struct kvmppc_book3s_shadow_vcpu *svcpu_get(struct kvm_vcpu *vcpu)
{
return to_book3s(vcpu)->shadow_vcpu;
}

static inline void svcpu_put(struct kvmppc_book3s_shadow_vcpu *svcpu)
{
}

#define PTE_SIZE 12
#define VSID_ALL 0
#define SR_INVALID 0x00000001 /* VSID 1 should always be unused */
Expand Down
8 changes: 7 additions & 1 deletion arch/powerpc/include/asm/kvm_book3s_64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,10 +21,16 @@
#define __ASM_KVM_BOOK3S_64_H__

#ifdef CONFIG_KVM_BOOK3S_PR
static inline struct kvmppc_book3s_shadow_vcpu *to_svcpu(struct kvm_vcpu *vcpu)
static inline struct kvmppc_book3s_shadow_vcpu *svcpu_get(struct kvm_vcpu *vcpu)
{
preempt_disable();
return &get_paca()->shadow_vcpu;
}

static inline void svcpu_put(struct kvmppc_book3s_shadow_vcpu *svcpu)
{
preempt_enable();
}
#endif

#define SPAPR_TCE_SHIFT 12
Expand Down
21 changes: 15 additions & 6 deletions arch/powerpc/kvm/book3s_32_mmu_host.c
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Original file line number Diff line number Diff line change
Expand Up @@ -151,13 +151,15 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte)
bool primary = false;
bool evict = false;
struct hpte_cache *pte;
int r = 0;

/* Get host physical address for gpa */
hpaddr = kvmppc_gfn_to_pfn(vcpu, orig_pte->raddr >> PAGE_SHIFT);
if (is_error_pfn(hpaddr)) {
printk(KERN_INFO "Couldn't get guest page for gfn %lx!\n",
orig_pte->eaddr);
return -EINVAL;
r = -EINVAL;
goto out;
}
hpaddr <<= PAGE_SHIFT;

Expand Down Expand Up @@ -249,7 +251,8 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte)

kvmppc_mmu_hpte_cache_map(vcpu, pte);

return 0;
out:
return r;
}

static struct kvmppc_sid_map *create_sid_map(struct kvm_vcpu *vcpu, u64 gvsid)
Expand Down Expand Up @@ -297,12 +300,14 @@ int kvmppc_mmu_map_segment(struct kvm_vcpu *vcpu, ulong eaddr)
u64 gvsid;
u32 sr;
struct kvmppc_sid_map *map;
struct kvmppc_book3s_shadow_vcpu *svcpu = to_svcpu(vcpu);
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
int r = 0;

if (vcpu->arch.mmu.esid_to_vsid(vcpu, esid, &gvsid)) {
/* Invalidate an entry */
svcpu->sr[esid] = SR_INVALID;
return -ENOENT;
r = -ENOENT;
goto out;
}

map = find_sid_vsid(vcpu, gvsid);
Expand All @@ -315,17 +320,21 @@ int kvmppc_mmu_map_segment(struct kvm_vcpu *vcpu, ulong eaddr)

dprintk_sr("MMU: mtsr %d, 0x%x\n", esid, sr);

return 0;
out:
svcpu_put(svcpu);
return r;
}

void kvmppc_mmu_flush_segments(struct kvm_vcpu *vcpu)
{
int i;
struct kvmppc_book3s_shadow_vcpu *svcpu = to_svcpu(vcpu);
struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);

dprintk_sr("MMU: flushing all segments (%d)\n", ARRAY_SIZE(svcpu->sr));
for (i = 0; i < ARRAY_SIZE(svcpu->sr); i++)
svcpu->sr[i] = SR_INVALID;

svcpu_put(svcpu);
}

void kvmppc_mmu_destroy(struct kvm_vcpu *vcpu)
Expand Down
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