KVM: PPC: Allow I/O mappings in memory slots

This provides for the case where userspace maps an I/O device into the
address range of a memory slot using a VM_PFNMAP mapping.  In that
case, we work out the pfn from vma->vm_pgoff, and record the cache
enable bits from vma->vm_page_prot in two low-order bits in the
slot_phys array entries.  Then, in kvmppc_h_enter() we check that the
cache bits in the HPTE that the guest wants to insert match the cache
bits in the slot_phys array entry.  However, we do allow the guest to
create what it thinks is a non-cacheable or write-through mapping to
memory that is actually cacheable, so that we can use normal system
memory as part of an emulated device later on.  In that case the actual
HPTE we insert is a cacheable HPTE.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 10920f7a2b8d363675fa9e34e97759774d1fa430..18b590d261ffa920721270b1c5a8b6939bec0b47 100644 (file)
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -113,6 +113,32 @@ static inline unsigned long hpte_page_size(unsigned long h, unsigned long l)
        return 0;                               /* error */
 }
 
+static inline int hpte_cache_flags_ok(unsigned long ptel, unsigned long io_type)
+{
+       unsigned int wimg = ptel & HPTE_R_WIMG;
+
+       /* Handle SAO */
+       if (wimg == (HPTE_R_W | HPTE_R_I | HPTE_R_M) &&
+           cpu_has_feature(CPU_FTR_ARCH_206))
+               wimg = HPTE_R_M;
+
+       if (!io_type)
+               return wimg == HPTE_R_M;
+
+       return (wimg & (HPTE_R_W | HPTE_R_I)) == io_type;
+}
+
+/* Return HPTE cache control bits corresponding to Linux pte bits */
+static inline unsigned long hpte_cache_bits(unsigned long pte_val)
+{
+#if _PAGE_NO_CACHE == HPTE_R_I && _PAGE_WRITETHRU == HPTE_R_W
+       return pte_val & (HPTE_R_W | HPTE_R_I);
+#else
+       return ((pte_val & _PAGE_NO_CACHE) ? HPTE_R_I : 0) +
+               ((pte_val & _PAGE_WRITETHRU) ? HPTE_R_W : 0);
+#endif
+}
+
 static inline bool slot_is_aligned(struct kvm_memory_slot *memslot,
                                   unsigned long pagesize)
 {

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 9252d5e3758de512beaa9305b1f618f3dd3c7005..243bc8038572dd73aedb0b45d7f2eb845534a3c7 100644 (file)
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -178,6 +178,8 @@ struct revmap_entry {
 
 /* Low-order bits in kvm->arch.slot_phys[][] */
 #define KVMPPC_PAGE_ORDER_MASK 0x1f
+#define KVMPPC_PAGE_NO_CACHE   HPTE_R_I        /* 0x20 */
+#define KVMPPC_PAGE_WRITETHRU  HPTE_R_W        /* 0x40 */
 #define KVMPPC_GOT_PAGE                0x80
 
 struct kvm_arch {

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index cc18f3d67a57636e1e4a52cf5c95cc549623e18f..b904c40a17bc33b7940802d21eaddd6a6b2b435c 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -199,7 +199,8 @@ static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
        struct page *page, *hpage, *pages[1];
        unsigned long s, pgsize;
        unsigned long *physp;
-       unsigned int got, pgorder;
+       unsigned int is_io, got, pgorder;
+       struct vm_area_struct *vma;
        unsigned long pfn, i, npages;
 
        physp = kvm->arch.slot_phys[memslot->id];
@@ -208,34 +209,51 @@ static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
        if (physp[gfn - memslot->base_gfn])
                return 0;
 
+       is_io = 0;
+       got = 0;
        page = NULL;
        pgsize = psize;
+       err = -EINVAL;
        start = gfn_to_hva_memslot(memslot, gfn);
 
        /* Instantiate and get the page we want access to */
        np = get_user_pages_fast(start, 1, 1, pages);
-       if (np != 1)
-               return -EINVAL;
-       page = pages[0];
-       got = KVMPPC_GOT_PAGE;
+       if (np != 1) {
+               /* Look up the vma for the page */
+               down_read(&current->mm->mmap_sem);
+               vma = find_vma(current->mm, start);
+               if (!vma || vma->vm_start > start ||
+                   start + psize > vma->vm_end ||
+                   !(vma->vm_flags & VM_PFNMAP))
+                       goto up_err;
+               is_io = hpte_cache_bits(pgprot_val(vma->vm_page_prot));
+               pfn = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+               /* check alignment of pfn vs. requested page size */
+               if (psize > PAGE_SIZE && (pfn & ((psize >> PAGE_SHIFT) - 1)))
+                       goto up_err;
+               up_read(&current->mm->mmap_sem);
 
-       /* See if this is a large page */
-       s = PAGE_SIZE;
-       if (PageHuge(page)) {
-               hpage = compound_head(page);
-               s <<= compound_order(hpage);
-               /* Get the whole large page if slot alignment is ok */
-               if (s > psize && slot_is_aligned(memslot, s) &&
-                   !(memslot->userspace_addr & (s - 1))) {
-                       start &= ~(s - 1);
-                       pgsize = s;
-                       page = hpage;
+       } else {
+               page = pages[0];
+               got = KVMPPC_GOT_PAGE;
+
+               /* See if this is a large page */
+               s = PAGE_SIZE;
+               if (PageHuge(page)) {
+                       hpage = compound_head(page);
+                       s <<= compound_order(hpage);
+                       /* Get the whole large page if slot alignment is ok */
+                       if (s > psize && slot_is_aligned(memslot, s) &&
+                           !(memslot->userspace_addr & (s - 1))) {
+                               start &= ~(s - 1);
+                               pgsize = s;
+                               page = hpage;
+                       }
                }
+               if (s < psize)
+                       goto out;
+               pfn = page_to_pfn(page);
        }
-       err = -EINVAL;
-       if (s < psize)
-               goto out;
-       pfn = page_to_pfn(page);
 
        npages = pgsize >> PAGE_SHIFT;
        pgorder = __ilog2(npages);
@@ -243,7 +261,8 @@ static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
        spin_lock(&kvm->arch.slot_phys_lock);
        for (i = 0; i < npages; ++i) {
                if (!physp[i]) {
-                       physp[i] = ((pfn + i) << PAGE_SHIFT) + got + pgorder;
+                       physp[i] = ((pfn + i) << PAGE_SHIFT) +
+                               got + is_io + pgorder;
                        got = 0;
                }
        }
@@ -257,6 +276,10 @@ static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
                put_page(page);
        }
        return err;
+
+ up_err:
+       up_read(&current->mm->mmap_sem);
+       return err;
 }
 
 /*

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index c086eb0fa992504be49d22d15f74978d0edd26c5..3f5b016490d06cf401bb6bc70effe04335f9807c 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -65,6 +65,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
        unsigned long g_ptel = ptel;
        struct kvm_memory_slot *memslot;
        unsigned long *physp, pte_size;
+       unsigned long is_io;
        bool realmode = vcpu->arch.vcore->vcore_state == VCORE_RUNNING;
 
        psize = hpte_page_size(pteh, ptel);
@@ -92,6 +93,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
        pa = *physp;
        if (!pa)
                return H_TOO_HARD;
+       is_io = pa & (HPTE_R_I | HPTE_R_W);
        pte_size = PAGE_SIZE << (pa & KVMPPC_PAGE_ORDER_MASK);
        pa &= PAGE_MASK;
 
@@ -104,9 +106,16 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
        ptel |= pa;
 
        /* Check WIMG */
-       if ((ptel & HPTE_R_WIMG) != HPTE_R_M &&
-           (ptel & HPTE_R_WIMG) != (HPTE_R_W | HPTE_R_I | HPTE_R_M))
-               return H_PARAMETER;
+       if (!hpte_cache_flags_ok(ptel, is_io)) {
+               if (is_io)
+                       return H_PARAMETER;
+               /*
+                * Allow guest to map emulated device memory as
+                * uncacheable, but actually make it cacheable.
+                */
+               ptel &= ~(HPTE_R_W|HPTE_R_I|HPTE_R_G);
+               ptel |= HPTE_R_M;
+       }
        pteh &= ~0x60UL;
        pteh |= HPTE_V_VALID;