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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: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Alexey Kardashevskiy 2019-03-29 16:43:26 +11:00 committed by Paul Mackerras
parent 2001825efc
commit e1a1ef84cd
4 changed files with 110 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/powerpc/include/asm/kvm_host.h
View File

@ -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];
};

2
arch/powerpc/include/asm/kvm_ppc.h
View File

@ -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,

72
arch/powerpc/kvm/book3s_64_vio.c
View File

@ -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++)
__free_page(stt->pages[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)
{

66
arch/powerpc/kvm/book3s_64_vio_hv.c
View File

@ -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];