Introduce the KVM_PGT_S2() helper macro to allow switching from the
traditional pgtable code to the pKVM version easily in mmu.c. The cost
of this 'indirection' is expected to be very minimal due to
is_protected_kvm_enabled() being backed by a static key.
With this, everything is in place to allow the delegation of
non-protected guest stage-2 page-tables to pKVM, so let's stop using the
host's kvm_s2_mmu from EL2 and enjoy the ride.
Signed-off-by: Quentin Perret <qperret@google.com>
---
arch/arm64/kvm/arm.c | 9 ++-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 -
arch/arm64/kvm/mmu.c | 104 +++++++++++++++++++++--------
3 files changed, 84 insertions(+), 31 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 2bf168b17a77..890c89874c6b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -506,7 +506,10 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
if (vcpu_has_run_once(vcpu) && unlikely(!irqchip_in_kernel(vcpu->kvm)))
static_branch_dec(&userspace_irqchip_in_use);
- kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
+ if (!is_protected_kvm_enabled())
+ kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
+ else
+ free_hyp_memcache(&vcpu->arch.pkvm_memcache);
kvm_timer_vcpu_terminate(vcpu);
kvm_pmu_vcpu_destroy(vcpu);
kvm_vgic_vcpu_destroy(vcpu);
@@ -578,6 +581,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
struct kvm_s2_mmu *mmu;
int *last_ran;
+ if (is_protected_kvm_enabled())
+ goto nommu;
+
if (vcpu_has_nv(vcpu))
kvm_vcpu_load_hw_mmu(vcpu);
@@ -598,6 +604,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
*last_ran = vcpu->vcpu_idx;
}
+nommu:
vcpu->cpu = cpu;
kvm_vgic_load(vcpu);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 1d8baa14ff1c..cf0fd83552c9 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -103,8 +103,6 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
/* Limit guest vector length to the maximum supported by the host. */
hyp_vcpu->vcpu.arch.sve_max_vl = min(host_vcpu->arch.sve_max_vl, kvm_host_sve_max_vl);
- hyp_vcpu->vcpu.arch.hw_mmu = host_vcpu->arch.hw_mmu;
-
hyp_vcpu->vcpu.arch.hcr_el2 = host_vcpu->arch.hcr_el2;
hyp_vcpu->vcpu.arch.mdcr_el2 = host_vcpu->arch.mdcr_el2;
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 80dd61038cc7..fcf8fdcccd22 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -15,6 +15,7 @@
#include <asm/kvm_arm.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_pgtable.h>
+#include <asm/kvm_pkvm.h>
#include <asm/kvm_ras.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
@@ -31,6 +32,14 @@ static phys_addr_t __ro_after_init hyp_idmap_vector;
static unsigned long __ro_after_init io_map_base;
+#define KVM_PGT_S2(fn, ...) \
+ ({ \
+ typeof(kvm_pgtable_stage2_ ## fn) *__fn = kvm_pgtable_stage2_ ## fn; \
+ if (is_protected_kvm_enabled()) \
+ __fn = pkvm_pgtable_ ## fn; \
+ __fn(__VA_ARGS__); \
+ })
+
static phys_addr_t __stage2_range_addr_end(phys_addr_t addr, phys_addr_t end,
phys_addr_t size)
{
@@ -147,7 +156,7 @@ static int kvm_mmu_split_huge_pages(struct kvm *kvm, phys_addr_t addr,
return -EINVAL;
next = __stage2_range_addr_end(addr, end, chunk_size);
- ret = kvm_pgtable_stage2_split(pgt, addr, next - addr, cache);
+ ret = KVM_PGT_S2(split, pgt, addr, next - addr, cache);
if (ret)
break;
} while (addr = next, addr != end);
@@ -168,15 +177,23 @@ static bool memslot_is_logging(struct kvm_memory_slot *memslot)
*/
int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
{
- kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu);
+ if (is_protected_kvm_enabled())
+ kvm_call_hyp_nvhe(__pkvm_tlb_flush_vmid, kvm->arch.pkvm.handle);
+ else
+ kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu);
return 0;
}
int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
gfn_t gfn, u64 nr_pages)
{
- kvm_tlb_flush_vmid_range(&kvm->arch.mmu,
- gfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
+ u64 size = nr_pages << PAGE_SHIFT;
+ u64 addr = gfn << PAGE_SHIFT;
+
+ if (is_protected_kvm_enabled())
+ kvm_call_hyp_nvhe(__pkvm_tlb_flush_vmid, kvm->arch.pkvm.handle);
+ else
+ kvm_tlb_flush_vmid_range(&kvm->arch.mmu, addr, size);
return 0;
}
@@ -225,7 +242,7 @@ static void stage2_free_unlinked_table_rcu_cb(struct rcu_head *head)
void *pgtable = page_to_virt(page);
s8 level = page_private(page);
- kvm_pgtable_stage2_free_unlinked(&kvm_s2_mm_ops, pgtable, level);
+ KVM_PGT_S2(free_unlinked, &kvm_s2_mm_ops, pgtable, level);
}
static void stage2_free_unlinked_table(void *addr, s8 level)
@@ -316,6 +333,12 @@ static void invalidate_icache_guest_page(void *va, size_t size)
* destroying the VM), otherwise another faulting VCPU may come in and mess
* with things behind our backs.
*/
+
+static int kvm_s2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
+{
+ return KVM_PGT_S2(unmap, pgt, addr, size);
+}
+
static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size,
bool may_block)
{
@@ -324,8 +347,7 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64
lockdep_assert_held_write(&kvm->mmu_lock);
WARN_ON(size & ~PAGE_MASK);
- WARN_ON(stage2_apply_range(mmu, start, end, kvm_pgtable_stage2_unmap,
- may_block));
+ WARN_ON(stage2_apply_range(mmu, start, end, kvm_s2_unmap, may_block));
}
void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
@@ -334,9 +356,14 @@ void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
__unmap_stage2_range(mmu, start, size, may_block);
}
+static int kvm_s2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
+{
+ return KVM_PGT_S2(flush, pgt, addr, size);
+}
+
void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
{
- stage2_apply_range_resched(mmu, addr, end, kvm_pgtable_stage2_flush);
+ stage2_apply_range_resched(mmu, addr, end, kvm_s2_flush);
}
static void stage2_flush_memslot(struct kvm *kvm,
@@ -942,10 +969,14 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
return -ENOMEM;
mmu->arch = &kvm->arch;
- err = kvm_pgtable_stage2_init(pgt, mmu, &kvm_s2_mm_ops);
+ err = KVM_PGT_S2(init, pgt, mmu, &kvm_s2_mm_ops);
if (err)
goto out_free_pgtable;
+ mmu->pgt = pgt;
+ if (is_protected_kvm_enabled())
+ return 0;
+
mmu->last_vcpu_ran = alloc_percpu(typeof(*mmu->last_vcpu_ran));
if (!mmu->last_vcpu_ran) {
err = -ENOMEM;
@@ -959,7 +990,6 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT;
mmu->split_page_cache.gfp_zero = __GFP_ZERO;
- mmu->pgt = pgt;
mmu->pgd_phys = __pa(pgt->pgd);
if (kvm_is_nested_s2_mmu(kvm, mmu))
@@ -968,7 +998,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
return 0;
out_destroy_pgtable:
- kvm_pgtable_stage2_destroy(pgt);
+ KVM_PGT_S2(destroy, pgt);
out_free_pgtable:
kfree(pgt);
return err;
@@ -1065,7 +1095,7 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
write_unlock(&kvm->mmu_lock);
if (pgt) {
- kvm_pgtable_stage2_destroy(pgt);
+ KVM_PGT_S2(destroy, pgt);
kfree(pgt);
}
}
@@ -1082,9 +1112,11 @@ static void *hyp_mc_alloc_fn(void *unused)
void free_hyp_memcache(struct kvm_hyp_memcache *mc)
{
- if (is_protected_kvm_enabled())
- __free_hyp_memcache(mc, hyp_mc_free_fn,
- kvm_host_va, NULL);
+ if (!is_protected_kvm_enabled())
+ return;
+
+ kfree(mc->mapping);
+ __free_hyp_memcache(mc, hyp_mc_free_fn, kvm_host_va, NULL);
}
int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages)
@@ -1092,6 +1124,12 @@ int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages)
if (!is_protected_kvm_enabled())
return 0;
+ if (!mc->mapping) {
+ mc->mapping = kzalloc(sizeof(struct pkvm_mapping), GFP_KERNEL_ACCOUNT);
+ if (!mc->mapping)
+ return -ENOMEM;
+ }
+
return __topup_hyp_memcache(mc, min_pages, hyp_mc_alloc_fn,
kvm_host_pa, NULL);
}
@@ -1130,8 +1168,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
break;
write_lock(&kvm->mmu_lock);
- ret = kvm_pgtable_stage2_map(pgt, addr, PAGE_SIZE, pa, prot,
- &cache, 0);
+ ret = KVM_PGT_S2(map, pgt, addr, PAGE_SIZE, pa, prot, &cache, 0);
write_unlock(&kvm->mmu_lock);
if (ret)
break;
@@ -1143,6 +1180,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
return ret;
}
+static int kvm_s2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
+{
+ return KVM_PGT_S2(wrprotect, pgt, addr, size);
+}
/**
* kvm_stage2_wp_range() - write protect stage2 memory region range
* @mmu: The KVM stage-2 MMU pointer
@@ -1151,7 +1192,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
*/
void kvm_stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
{
- stage2_apply_range_resched(mmu, addr, end, kvm_pgtable_stage2_wrprotect);
+ stage2_apply_range_resched(mmu, addr, end, kvm_s2_wrprotect);
}
/**
@@ -1431,9 +1472,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
unsigned long mmu_seq;
phys_addr_t ipa = fault_ipa;
struct kvm *kvm = vcpu->kvm;
- struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
struct vm_area_struct *vma;
short vma_shift;
+ void *memcache;
gfn_t gfn;
kvm_pfn_t pfn;
bool logging_active = memslot_is_logging(memslot);
@@ -1460,8 +1501,15 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* and a write fault needs to collapse a block entry into a table.
*/
if (!fault_is_perm || (logging_active && write_fault)) {
- ret = kvm_mmu_topup_memory_cache(memcache,
- kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu));
+ int min_pages = kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu);
+
+ if (!is_protected_kvm_enabled()) {
+ memcache = &vcpu->arch.mmu_page_cache;
+ ret = kvm_mmu_topup_memory_cache(memcache, min_pages);
+ } else {
+ memcache = &vcpu->arch.pkvm_memcache;
+ ret = topup_hyp_memcache(memcache, min_pages);
+ }
if (ret)
return ret;
}
@@ -1482,7 +1530,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* logging_active is guaranteed to never be true for VM_PFNMAP
* memslots.
*/
- if (logging_active) {
+ if (logging_active || is_protected_kvm_enabled()) {
force_pte = true;
vma_shift = PAGE_SHIFT;
} else {
@@ -1684,9 +1732,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* PTE, which will be preserved.
*/
prot &= ~KVM_NV_GUEST_MAP_SZ;
- ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot, flags);
+ ret = KVM_PGT_S2(relax_perms, pgt, fault_ipa, prot, flags);
} else {
- ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize,
+ ret = KVM_PGT_S2(map, pgt, fault_ipa, vma_pagesize,
__pfn_to_phys(pfn), prot,
memcache, flags);
}
@@ -1715,7 +1763,7 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
read_lock(&vcpu->kvm->mmu_lock);
mmu = vcpu->arch.hw_mmu;
- pte = kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa, flags);
+ pte = KVM_PGT_S2(mkyoung, mmu->pgt, fault_ipa, flags);
read_unlock(&vcpu->kvm->mmu_lock);
if (kvm_pte_valid(pte))
@@ -1758,7 +1806,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
}
/* Falls between the IPA range and the PARange? */
- if (fault_ipa >= BIT_ULL(vcpu->arch.hw_mmu->pgt->ia_bits)) {
+ if (fault_ipa >= BIT_ULL(VTCR_EL2_IPA(vcpu->arch.hw_mmu->vtcr))) {
fault_ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);
if (is_iabt)
@@ -1924,7 +1972,7 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
if (!kvm->arch.mmu.pgt)
return false;
- return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt,
+ return KVM_PGT_S2(test_clear_young, kvm->arch.mmu.pgt,
range->start << PAGE_SHIFT,
size, true);
/*
@@ -1940,7 +1988,7 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
if (!kvm->arch.mmu.pgt)
return false;
- return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt,
+ return KVM_PGT_S2(test_clear_young, kvm->arch.mmu.pgt,
range->start << PAGE_SHIFT,
size, false);
}
--
2.47.0.163.g1226f6d8fa-googHi Quentin,
kernel test robot noticed the following build warnings:
[auto build test WARNING on v6.12-rc6]
[also build test WARNING on linus/master]
[cannot apply to kvmarm/next next-20241104]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Quentin-Perret/KVM-arm64-Change-the-layout-of-enum-pkvm_page_state/20241104-213817
base: v6.12-rc6
patch link: https://lore.kernel.org/r/20241104133204.85208-19-qperret%40google.com
patch subject: [PATCH 18/18] KVM: arm64: Plumb the pKVM MMU in KVM
config: arm64-randconfig-002-20241105 (https://download.01.org/0day-ci/archive/20241105/202411051325.EBkzE0th-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241105/202411051325.EBkzE0th-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202411051325.EBkzE0th-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> arch/arm64/kvm/mmu.c:338: warning: Function parameter or struct member 'pgt' not described in 'kvm_s2_unmap'
>> arch/arm64/kvm/mmu.c:338: warning: Function parameter or struct member 'addr' not described in 'kvm_s2_unmap'
>> arch/arm64/kvm/mmu.c:338: warning: expecting prototype for __unmap_stage2_range(). Prototype was for kvm_s2_unmap() instead
vim +338 arch/arm64/kvm/mmu.c
299
300 /*
301 * Unmapping vs dcache management:
302 *
303 * If a guest maps certain memory pages as uncached, all writes will
304 * bypass the data cache and go directly to RAM. However, the CPUs
305 * can still speculate reads (not writes) and fill cache lines with
306 * data.
307 *
308 * Those cache lines will be *clean* cache lines though, so a
309 * clean+invalidate operation is equivalent to an invalidate
310 * operation, because no cache lines are marked dirty.
311 *
312 * Those clean cache lines could be filled prior to an uncached write
313 * by the guest, and the cache coherent IO subsystem would therefore
314 * end up writing old data to disk.
315 *
316 * This is why right after unmapping a page/section and invalidating
317 * the corresponding TLBs, we flush to make sure the IO subsystem will
318 * never hit in the cache.
319 *
320 * This is all avoided on systems that have ARM64_HAS_STAGE2_FWB, as
321 * we then fully enforce cacheability of RAM, no matter what the guest
322 * does.
323 */
324 /**
325 * __unmap_stage2_range -- Clear stage2 page table entries to unmap a range
326 * @mmu: The KVM stage-2 MMU pointer
327 * @start: The intermediate physical base address of the range to unmap
328 * @size: The size of the area to unmap
329 * @may_block: Whether or not we are permitted to block
330 *
331 * Clear a range of stage-2 mappings, lowering the various ref-counts. Must
332 * be called while holding mmu_lock (unless for freeing the stage2 pgd before
333 * destroying the VM), otherwise another faulting VCPU may come in and mess
334 * with things behind our backs.
335 */
336
337 static int kvm_s2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
> 338 {
339 return KVM_PGT_S2(unmap, pgt, addr, size);
340 }
341
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Tuesday 05 Nov 2024 at 13:53:22 (+0800), kernel test robot wrote:
> Hi Quentin,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on v6.12-rc6]
> [also build test WARNING on linus/master]
> [cannot apply to kvmarm/next next-20241104]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Quentin-Perret/KVM-arm64-Change-the-layout-of-enum-pkvm_page_state/20241104-213817
> base: v6.12-rc6
> patch link: https://lore.kernel.org/r/20241104133204.85208-19-qperret%40google.com
> patch subject: [PATCH 18/18] KVM: arm64: Plumb the pKVM MMU in KVM
> config: arm64-randconfig-002-20241105 (https://download.01.org/0day-ci/archive/20241105/202411051325.EBkzE0th-lkp@intel.com/config)
> compiler: aarch64-linux-gcc (GCC) 14.1.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241105/202411051325.EBkzE0th-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202411051325.EBkzE0th-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> >> arch/arm64/kvm/mmu.c:338: warning: Function parameter or struct member 'pgt' not described in 'kvm_s2_unmap'
> >> arch/arm64/kvm/mmu.c:338: warning: Function parameter or struct member 'addr' not described in 'kvm_s2_unmap'
> >> arch/arm64/kvm/mmu.c:338: warning: expecting prototype for __unmap_stage2_range(). Prototype was for kvm_s2_unmap() instead
>
>
> vim +338 arch/arm64/kvm/mmu.c
>
> 299
> 300 /*
> 301 * Unmapping vs dcache management:
> 302 *
> 303 * If a guest maps certain memory pages as uncached, all writes will
> 304 * bypass the data cache and go directly to RAM. However, the CPUs
> 305 * can still speculate reads (not writes) and fill cache lines with
> 306 * data.
> 307 *
> 308 * Those cache lines will be *clean* cache lines though, so a
> 309 * clean+invalidate operation is equivalent to an invalidate
> 310 * operation, because no cache lines are marked dirty.
> 311 *
> 312 * Those clean cache lines could be filled prior to an uncached write
> 313 * by the guest, and the cache coherent IO subsystem would therefore
> 314 * end up writing old data to disk.
> 315 *
> 316 * This is why right after unmapping a page/section and invalidating
> 317 * the corresponding TLBs, we flush to make sure the IO subsystem will
> 318 * never hit in the cache.
> 319 *
> 320 * This is all avoided on systems that have ARM64_HAS_STAGE2_FWB, as
> 321 * we then fully enforce cacheability of RAM, no matter what the guest
> 322 * does.
> 323 */
> 324 /**
> 325 * __unmap_stage2_range -- Clear stage2 page table entries to unmap a range
> 326 * @mmu: The KVM stage-2 MMU pointer
> 327 * @start: The intermediate physical base address of the range to unmap
> 328 * @size: The size of the area to unmap
> 329 * @may_block: Whether or not we are permitted to block
> 330 *
> 331 * Clear a range of stage-2 mappings, lowering the various ref-counts. Must
> 332 * be called while holding mmu_lock (unless for freeing the stage2 pgd before
> 333 * destroying the VM), otherwise another faulting VCPU may come in and mess
> 334 * with things behind our backs.
> 335 */
> 336
> 337 static int kvm_s2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
> > 338 {
> 339 return KVM_PGT_S2(unmap, pgt, addr, size);
> 340 }
> 341
Oops, yes, that broke the kerneldoc comment, I'll fix in v2.
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