Commit f2fd125d authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Gleb Natapov
Browse files

KVM: MMU: store generation-number into mmio spte 



Store the generation-number into bit3 ~ bit11 and bit52 ~ bit61, totally
19 bits can be used, it should be enough for nearly all most common cases

In this patch, the generation-number is always 0, it will be changed in
the later patch

[Gleb: masking generation bits from spte in get_mmio_spte_gfn() and
       get_mmio_spte_access()]

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: default avatarGleb Natapov <gleb@redhat.com>
Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 885032b9

arch/x86/kvm/mmu.c

+52 −12
Original line number Diff line number Diff line
@@ -197,15 +197,52 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask) 
}

EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);



static void mark_mmio_spte(u64 *sptep, u64 gfn, unsigned access)

/*

 * spte bits of bit 3 ~ bit 11 are used as low 9 bits of generation number,

 * the bits of bits 52 ~ bit 61 are used as high 10 bits of generation

 * number.

 */

#define MMIO_SPTE_GEN_LOW_SHIFT		3

#define MMIO_SPTE_GEN_HIGH_SHIFT	52



#define MMIO_GEN_LOW_SHIFT		9

#define MMIO_GEN_LOW_MASK		((1 << MMIO_GEN_LOW_SHIFT) - 1)

#define MMIO_MAX_GEN			((1 << 19) - 1)



static u64 generation_mmio_spte_mask(unsigned int gen)

{

	u64 mask;



	WARN_ON(gen > MMIO_MAX_GEN);



	mask = (gen & MMIO_GEN_LOW_MASK) << MMIO_SPTE_GEN_LOW_SHIFT;

	mask |= ((u64)gen >> MMIO_GEN_LOW_SHIFT) << MMIO_SPTE_GEN_HIGH_SHIFT;

	return mask;

}



static unsigned int get_mmio_spte_generation(u64 spte)

{

	unsigned int gen;



	spte &= ~shadow_mmio_mask;



	gen = (spte >> MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_GEN_LOW_MASK;

	gen |= (spte >> MMIO_SPTE_GEN_HIGH_SHIFT) << MMIO_GEN_LOW_SHIFT;

	return gen;

}



static void mark_mmio_spte(struct kvm *kvm, u64 *sptep, u64 gfn,

			   unsigned access)

{

	struct kvm_mmu_page *sp =  page_header(__pa(sptep));

	u64 mask = generation_mmio_spte_mask(0);



	access &= ACC_WRITE_MASK | ACC_USER_MASK;



	mask |= shadow_mmio_mask | access | gfn << PAGE_SHIFT;

	sp->mmio_cached = true;

	trace_mark_mmio_spte(sptep, gfn, access);

	mmu_spte_set(sptep, shadow_mmio_mask | access | gfn << PAGE_SHIFT);



	trace_mark_mmio_spte(sptep, gfn, access, 0);

	mmu_spte_set(sptep, mask);

}



static bool is_mmio_spte(u64 spte)
@@ -215,18 +252,21 @@ static bool is_mmio_spte(u64 spte) 


static gfn_t get_mmio_spte_gfn(u64 spte)

{

	return (spte & ~shadow_mmio_mask) >> PAGE_SHIFT;

	u64 mask = generation_mmio_spte_mask(MMIO_MAX_GEN) | shadow_mmio_mask;

	return (spte & ~mask) >> PAGE_SHIFT;

}



static unsigned get_mmio_spte_access(u64 spte)

{

	return (spte & ~shadow_mmio_mask) & ~PAGE_MASK;

	u64 mask = generation_mmio_spte_mask(MMIO_MAX_GEN) | shadow_mmio_mask;

	return (spte & ~mask) & ~PAGE_MASK;

}



static bool set_mmio_spte(u64 *sptep, gfn_t gfn, pfn_t pfn, unsigned access)

static bool set_mmio_spte(struct kvm *kvm, u64 *sptep, gfn_t gfn,

			  pfn_t pfn, unsigned access)

{

	if (unlikely(is_noslot_pfn(pfn))) {

		mark_mmio_spte(sptep, gfn, access);

		mark_mmio_spte(kvm, sptep, gfn, access);

		return true;

	}
@@ -2364,7 +2404,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, 
	u64 spte;

	int ret = 0;



	if (set_mmio_spte(sptep, gfn, pfn, pte_access))

	if (set_mmio_spte(vcpu->kvm, sptep, gfn, pfn, pte_access))

		return 0;



	spte = PT_PRESENT_MASK;
@@ -3427,8 +3467,8 @@ static inline void protect_clean_gpte(unsigned *access, unsigned gpte) 
	*access &= mask;

}



static bool sync_mmio_spte(u64 *sptep, gfn_t gfn, unsigned access,

			   int *nr_present)

static bool sync_mmio_spte(struct kvm *kvm, u64 *sptep, gfn_t gfn,

			   unsigned access, int *nr_present)

{

	if (unlikely(is_mmio_spte(*sptep))) {

		if (gfn != get_mmio_spte_gfn(*sptep)) {
@@ -3437,7 +3477,7 @@ static bool sync_mmio_spte(u64 *sptep, gfn_t gfn, unsigned access, 
		}



		(*nr_present)++;

		mark_mmio_spte(sptep, gfn, access);

		mark_mmio_spte(kvm, sptep, gfn, access);

		return true;

	}

arch/x86/kvm/mmutrace.h

+6 −4
Original line number Diff line number Diff line
@@ -199,23 +199,25 @@ DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page, 


TRACE_EVENT(

	mark_mmio_spte,

	TP_PROTO(u64 *sptep, gfn_t gfn, unsigned access),

	TP_ARGS(sptep, gfn, access),

	TP_PROTO(u64 *sptep, gfn_t gfn, unsigned access, unsigned int gen),

	TP_ARGS(sptep, gfn, access, gen),



	TP_STRUCT__entry(

		__field(void *, sptep)

		__field(gfn_t, gfn)

		__field(unsigned, access)

		__field(unsigned int, gen)

	),



	TP_fast_assign(

		__entry->sptep = sptep;

		__entry->gfn = gfn;

		__entry->access = access;

		__entry->gen = gen;

	),



	TP_printk("sptep:%p gfn %llx access %x", __entry->sptep, __entry->gfn,

		  __entry->access)

	TP_printk("sptep:%p gfn %llx access %x gen %x", __entry->sptep,

		  __entry->gfn, __entry->access, __entry->gen)

);



TRACE_EVENT(

arch/x86/kvm/paging_tmpl.h

+2 −1
Original line number Diff line number Diff line
@@ -792,7 +792,8 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 
		pte_access &= gpte_access(vcpu, gpte);

		protect_clean_gpte(&pte_access, gpte);



		if (sync_mmio_spte(&sp->spt[i], gfn, pte_access, &nr_present))

		if (sync_mmio_spte(vcpu->kvm, &sp->spt[i], gfn, pte_access,

		      &nr_present))

			continue;



		if (gfn != sp->gfns[i]) {

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