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Commit e1a1ef84 authored by Alexey Kardashevskiy's avatar Alexey Kardashevskiy Committed by Paul Mackerras
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KVM: PPC: Book3S: Allocate guest TCEs on demand too 



We already allocate hardware TCE tables in multiple levels and skip
intermediate levels when we can, now it is a turn of the KVM TCE tables.
Thankfully these are allocated already in 2 levels.

This moves the table's last level allocation from the creating helper to
kvmppc_tce_put() and kvm_spapr_tce_fault(). Since such allocation cannot
be done in real mode, this creates a virtual mode version of
kvmppc_tce_put() which handles allocations.

This adds kvmppc_rm_ioba_validate() to do an additional test if
the consequent kvmppc_tce_put() needs a page which has not been allocated;
if this is the case, we bail out to virtual mode handlers.

The allocations are protected by a new mutex as kvm->lock is not suitable
for the task because the fault handler is called with the mmap_sem held
but kvmhv_setup_mmu() locks kvm->lock and mmap_sem in the reverse order.

Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent 2001825e

arch/powerpc/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -201,6 +201,8 @@ struct kvmppc_spapr_tce_iommu_table { 
	struct kref kref;

};



#define TCES_PER_PAGE	(PAGE_SIZE / sizeof(u64))



struct kvmppc_spapr_tce_table {

	struct list_head list;

	struct kvm *kvm;
@@ -210,6 +212,7 @@ struct kvmppc_spapr_tce_table { 
	u64 offset;		/* in pages */

	u64 size;		/* window size in pages */

	struct list_head iommu_tables;

	struct mutex alloc_lock;

	struct page *pages[0];

};

arch/powerpc/include/asm/kvm_ppc.h

+0 −2
Original line number Diff line number Diff line
@@ -197,8 +197,6 @@ extern struct kvmppc_spapr_tce_table *kvmppc_find_table( 
		(iommu_tce_check_ioba((stt)->page_shift, (stt)->offset, \

				(stt)->size, (ioba), (npages)) ?        \

				H_PARAMETER : H_SUCCESS)

extern void kvmppc_tce_put(struct kvmppc_spapr_tce_table *tt,

		unsigned long idx, unsigned long tce);

extern long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,

			     unsigned long ioba, unsigned long tce);

extern long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,

arch/powerpc/kvm/book3s_64_vio.c

+58 −14
Original line number Diff line number Diff line
@@ -228,11 +228,33 @@ static void release_spapr_tce_table(struct rcu_head *head) 
	unsigned long i, npages = kvmppc_tce_pages(stt->size);



	for (i = 0; i < npages; i++)

		if (stt->pages[i])

			__free_page(stt->pages[i]);



	kfree(stt);

}



static struct page *kvm_spapr_get_tce_page(struct kvmppc_spapr_tce_table *stt,

		unsigned long sttpage)

{

	struct page *page = stt->pages[sttpage];



	if (page)

		return page;



	mutex_lock(&stt->alloc_lock);

	page = stt->pages[sttpage];

	if (!page) {

		page = alloc_page(GFP_KERNEL | __GFP_ZERO);

		WARN_ON_ONCE(!page);

		if (page)

			stt->pages[sttpage] = page;

	}

	mutex_unlock(&stt->alloc_lock);



	return page;

}



static vm_fault_t kvm_spapr_tce_fault(struct vm_fault *vmf)

{

	struct kvmppc_spapr_tce_table *stt = vmf->vma->vm_file->private_data;
@@ -241,7 +263,10 @@ static vm_fault_t kvm_spapr_tce_fault(struct vm_fault *vmf) 
	if (vmf->pgoff >= kvmppc_tce_pages(stt->size))

		return VM_FAULT_SIGBUS;



	page = stt->pages[vmf->pgoff];

	page = kvm_spapr_get_tce_page(stt, vmf->pgoff);

	if (!page)

		return VM_FAULT_OOM;



	get_page(page);

	vmf->page = page;

	return 0;
@@ -296,7 +321,6 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, 
	struct kvmppc_spapr_tce_table *siter;

	unsigned long npages, size = args->size;

	int ret = -ENOMEM;

	int i;



	if (!args->size || args->page_shift < 12 || args->page_shift > 34 ||

		(args->offset + args->size > (ULLONG_MAX >> args->page_shift)))
@@ -318,14 +342,9 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, 
	stt->offset = args->offset;

	stt->size = size;

	stt->kvm = kvm;

	mutex_init(&stt->alloc_lock);

	INIT_LIST_HEAD_RCU(&stt->iommu_tables);



	for (i = 0; i < npages; i++) {

		stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);

		if (!stt->pages[i])

			goto fail;

	}



	mutex_lock(&kvm->lock);



	/* Check this LIOBN hasn't been previously allocated */
@@ -352,11 +371,6 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, 
	if (ret >= 0)

		return ret;



 fail:

	for (i = 0; i < npages; i++)

		if (stt->pages[i])

			__free_page(stt->pages[i]);



	kfree(stt);

 fail_acct:

	kvmppc_account_memlimit(kvmppc_stt_pages(npages), false);
@@ -413,6 +427,36 @@ static long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt, 
	return H_SUCCESS;

}



/*

 * Handles TCE requests for emulated devices.

 * Puts guest TCE values to the table and expects user space to convert them.

 * Cannot fail so kvmppc_tce_validate must be called before it.

 */

static void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt,

		unsigned long idx, unsigned long tce)

{

	struct page *page;

	u64 *tbl;

	unsigned long sttpage;



	idx -= stt->offset;

	sttpage = idx / TCES_PER_PAGE;

	page = stt->pages[sttpage];



	if (!page) {

		/* We allow any TCE, not just with read|write permissions */

		if (!tce)

			return;



		page = kvm_spapr_get_tce_page(stt, sttpage);

		if (!page)

			return;

	}

	tbl = page_to_virt(page);



	tbl[idx % TCES_PER_PAGE] = tce;

}



static void kvmppc_clear_tce(struct mm_struct *mm, struct iommu_table *tbl,

		unsigned long entry)

{

arch/powerpc/kvm/book3s_64_vio_hv.c

+49 −17
Original line number Diff line number Diff line
@@ -66,8 +66,6 @@ 


#endif



#define TCES_PER_PAGE	(PAGE_SIZE / sizeof(u64))



/*

 * Finds a TCE table descriptor by LIOBN.

 *
@@ -148,7 +146,6 @@ static long kvmppc_rm_tce_validate(struct kvmppc_spapr_tce_table *stt, 


	return H_SUCCESS;

}

#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */



/* Note on the use of page_address() in real mode,

 *
@@ -180,13 +177,9 @@ static u64 *kvmppc_page_address(struct page *page) 
/*

 * Handles TCE requests for emulated devices.

 * Puts guest TCE values to the table and expects user space to convert them.

 * Called in both real and virtual modes.

 * Cannot fail so kvmppc_tce_validate must be called before it.

 *

 * WARNING: This will be called in real-mode on HV KVM and virtual

 *          mode on PR KVM

 * Cannot fail so kvmppc_rm_tce_validate must be called before it.

 */

void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt,

static void kvmppc_rm_tce_put(struct kvmppc_spapr_tce_table *stt,

		unsigned long idx, unsigned long tce)

{

	struct page *page;
@@ -194,13 +187,48 @@ void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt, 


	idx -= stt->offset;

	page = stt->pages[idx / TCES_PER_PAGE];

	/*

	 * page must not be NULL in real mode,

	 * kvmppc_rm_ioba_validate() must have taken care of this.

	 */

	WARN_ON_ONCE_RM(!page);

	tbl = kvmppc_page_address(page);



	tbl[idx % TCES_PER_PAGE] = tce;

}

EXPORT_SYMBOL_GPL(kvmppc_tce_put);



#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE

/*

 * TCEs pages are allocated in kvmppc_rm_tce_put() which won't be able to do so

 * in real mode.

 * Check if kvmppc_rm_tce_put() can succeed in real mode, i.e. a TCEs page is

 * allocated or not required (when clearing a tce entry).

 */

static long kvmppc_rm_ioba_validate(struct kvmppc_spapr_tce_table *stt,

		unsigned long ioba, unsigned long npages, bool clearing)

{

	unsigned long i, idx, sttpage, sttpages;

	unsigned long ret = kvmppc_ioba_validate(stt, ioba, npages);



	if (ret)

		return ret;

	/*

	 * clearing==true says kvmppc_rm_tce_put won't be allocating pages

	 * for empty tces.

	 */

	if (clearing)

		return H_SUCCESS;



	idx = (ioba >> stt->page_shift) - stt->offset;

	sttpage = idx / TCES_PER_PAGE;

	sttpages = _ALIGN_UP(idx % TCES_PER_PAGE + npages, TCES_PER_PAGE) /

			TCES_PER_PAGE;

	for (i = sttpage; i < sttpage + sttpages; ++i)

		if (!stt->pages[i])

			return H_TOO_HARD;



	return H_SUCCESS;

}



static long iommu_tce_xchg_rm(struct mm_struct *mm, struct iommu_table *tbl,

		unsigned long entry, unsigned long *hpa,

		enum dma_data_direction *direction)
@@ -378,7 +406,7 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, 
	if (!stt)

		return H_TOO_HARD;



	ret = kvmppc_ioba_validate(stt, ioba, 1);

	ret = kvmppc_rm_ioba_validate(stt, ioba, 1, tce == 0);

	if (ret != H_SUCCESS)

		return ret;
@@ -406,7 +434,7 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, 
		}

	}



	kvmppc_tce_put(stt, entry, tce);

	kvmppc_rm_tce_put(stt, entry, tce);



	return H_SUCCESS;

}
@@ -477,7 +505,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, 
	if (tce_list & (SZ_4K - 1))

		return H_PARAMETER;



	ret = kvmppc_ioba_validate(stt, ioba, npages);

	ret = kvmppc_rm_ioba_validate(stt, ioba, npages, false);

	if (ret != H_SUCCESS)

		return ret;
@@ -554,7 +582,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, 
			}

		}



		kvmppc_tce_put(stt, entry + i, tce);

		kvmppc_rm_tce_put(stt, entry + i, tce);

	}



unlock_exit:
@@ -580,7 +608,7 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu, 
	if (!stt)

		return H_TOO_HARD;



	ret = kvmppc_ioba_validate(stt, ioba, npages);

	ret = kvmppc_rm_ioba_validate(stt, ioba, npages, tce_value == 0);

	if (ret != H_SUCCESS)

		return ret;
@@ -607,7 +635,7 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu, 
	}



	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))

		kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);

		kvmppc_rm_tce_put(stt, ioba >> stt->page_shift, tce_value);



	return H_SUCCESS;

}
@@ -632,6 +660,10 @@ long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigned long liobn, 


	idx = (ioba >> stt->page_shift) - stt->offset;

	page = stt->pages[idx / TCES_PER_PAGE];

	if (!page) {

		vcpu->arch.regs.gpr[4] = 0;

		return H_SUCCESS;

	}

	tbl = (u64 *)page_address(page);



	vcpu->arch.regs.gpr[4] = tbl[idx % TCES_PER_PAGE];