This patch is a beginning attempt to support SMP guests. So far we only
add locking for the second stage PGD stored on the kvm_arch struct.
WARNING: This code is untested and does not yet support SMP guests.
Signed-off-by: Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/kvm_host.h | 12 ++++++--
arch/arm/kvm/arm.c | 1 +
arch/arm/kvm/mmu.c | 57 +++++++++++++++++++++++++--------------
3 files changed, 47 insertions(+), 23 deletions(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 7fcc412..555a6f1 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -31,9 +31,15 @@ struct kvm_vcpu;
u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
struct kvm_arch {
- u32 vmid; /* The VMID used for the virt. memory system */
- pgd_t *pgd; /* 1-level 2nd stage table */
- u64 vttbr; /* VTTBR value associated with above pgd and vmid */
+ /* The VMID used for the virt. memory system */
+ u32 vmid;
+
+ /* 1-level 2nd stage table and lock */
+ struct mutex pgd_mutex;
+ pgd_t *pgd;
+
+ /* VTTBR value associated with above pgd and vmid */
+ u64 vttbr;
};
#define EXCEPTION_NONE 0
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9c5c38e..14ccc4d 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -119,6 +119,7 @@ int kvm_arch_init_vm(struct kvm *kvm)
ret = kvm_alloc_stage2_pgd(kvm);
if (ret)
goto out_fail_alloc;
+ mutex_init(&kvm->arch.pgd_mutex);
pgd_phys = virt_to_phys(kvm->arch.pgd);
kvm->arch.vttbr = pgd_phys & ((1LLU << 40) - 1) & ~((2 << VTTBR_X) - 1);
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 50c9571..baeb8a1 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -177,6 +177,9 @@ out:
* Allocates the 1st level table only of size defined by PGD2_ORDER (can
* support either full 40-bit input addresses or limited to 32-bit input
* addresses). Clears the allocated pages.
+ *
+ * Note we don't need locking here as this is only called when the VM is
+ * destroyed, which can only be done once.
*/
int kvm_alloc_stage2_pgd(struct kvm *kvm)
{
@@ -204,6 +207,9 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
* Walks the level-1 page table pointed to by kvm->arch.pgd and frees all
* underlying level-2 and level-3 tables before freeing the actual level-1 table
* and setting the struct pointer to NULL.
+ *
+ * Note we don't need locking here as this is only called when the VM is
+ * destroyed, which can only be done once.
*/
void kvm_free_stage2_pgd(struct kvm *kvm)
{
@@ -239,49 +245,38 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
kvm->arch.pgd = NULL;
}
-static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
- gfn_t gfn, struct kvm_memory_slot *memslot)
+static int __user_mem_abort(struct kvm *kvm, phys_addr_t addr, pfn_t pfn)
{
- pfn_t pfn;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte, new_pte;
- pfn = gfn_to_pfn(vcpu->kvm, gfn);
-
- if (is_error_pfn(pfn)) {
- kvm_err(-EFAULT, "Guest gfn %u (0x%08lx) does not have "
- "corresponding host mapping",
- gfn, gfn << PAGE_SHIFT);
- return -EFAULT;
- }
-
/* Create 2nd stage page table mapping - Level 1 */
- pgd = vcpu->kvm->arch.pgd + pgd_index(fault_ipa);
- pud = pud_offset(pgd, fault_ipa);
+ pgd = kvm->arch.pgd + pgd_index(addr);
+ pud = pud_offset(pgd, addr);
if (pud_none(*pud)) {
- pmd = pmd_alloc_one(NULL, fault_ipa);
+ pmd = pmd_alloc_one(NULL, addr);
if (!pmd) {
kvm_err(-ENOMEM, "Cannot allocate 2nd stage pmd");
return -ENOMEM;
}
pud_populate(NULL, pud, pmd);
- pmd += pmd_index(fault_ipa);
+ pmd += pmd_index(addr);
} else
- pmd = pmd_offset(pud, fault_ipa);
+ pmd = pmd_offset(pud, addr);
/* Create 2nd stage page table mapping - Level 2 */
if (pmd_none(*pmd)) {
- pte = pte_alloc_one_kernel(NULL, fault_ipa);
+ pte = pte_alloc_one_kernel(NULL, addr);
if (!pte) {
kvm_err(-ENOMEM, "Cannot allocate 2nd stage pte");
return -ENOMEM;
}
pmd_populate_kernel(NULL, pmd, pte);
- pte += pte_index(fault_ipa);
+ pte += pte_index(addr);
} else
- pte = pte_offset_kernel(pmd, fault_ipa);
+ pte = pte_offset_kernel(pmd, addr);
/* Create 2nd stage page table mapping - Level 3 */
new_pte = pfn_pte(pfn, PAGE_KVM_GUEST);
@@ -290,6 +285,28 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
return 0;
}
+static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
+ gfn_t gfn, struct kvm_memory_slot *memslot)
+{
+ pfn_t pfn;
+ int ret;
+
+ pfn = gfn_to_pfn(vcpu->kvm, gfn);
+
+ if (is_error_pfn(pfn)) {
+ kvm_err(-EFAULT, "Guest gfn %u (0x%08lx) does not have "
+ "corresponding host mapping",
+ gfn, gfn << PAGE_SHIFT);
+ return -EFAULT;
+ }
+
+ mutex_lock(&vcpu->kvm->arch.pgd_mutex);
+ ret = __user_mem_abort(vcpu->kvm, fault_ipa, pfn);
+ mutex_unlock(&vcpu->kvm->arch.pgd_mutex);
+
+ return ret;
+}
+
/**
* kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
* @vcpu: The VCPU pointer
--
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