[RFC PATCH v2 46/58] KVM: arm64: Add function to topup generic allocator

[Mostafa Saleh]

Soon, IOMMU driver might need to topup the IOMMU pool from map_pages
IOMMU operation, which has a gfp flag is it might be called from
atomic context, add a function to topup an allocator with an ID
that also accepts gfp flags.

Signed-off-by: Mostafa Saleh <smostafa at google.com>
---
 arch/arm64/include/asm/kvm_host.h |  4 ++++
 arch/arm64/kvm/mmu.c              | 20 ++++++++++++++++++++
 arch/arm64/kvm/pkvm.c             | 20 ++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index a3b5d8dd8995..59a23828bd0e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -155,6 +155,8 @@ static inline void __free_hyp_memcache(struct kvm_hyp_memcache *mc,
 
 void free_hyp_memcache(struct kvm_hyp_memcache *mc);
 int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages, unsigned long order);
+int topup_hyp_memcache_gfp(struct kvm_hyp_memcache *mc, unsigned long min_pages,
+			   unsigned long order, gfp_t gfp);
 
 static inline void init_hyp_memcache(struct kvm_hyp_memcache *mc)
 {
@@ -1628,6 +1630,8 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val);
 #define HYP_ALLOC_MGT_IOMMU_ID		1
 
 unsigned long __pkvm_reclaim_hyp_alloc_mgt(unsigned long nr_pages);
+int __pkvm_topup_hyp_alloc_mgt_gfp(unsigned long id, unsigned long nr_pages,
+				   unsigned long sz_alloc, gfp_t gfp);
 
 struct kvm_iommu_driver {
 	int (*init_driver)(void);
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index ef7e8c156afb..229338877c59 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1225,6 +1225,11 @@ static void *hyp_mc_alloc_fn(void *flags, unsigned long order)
 	return addr;
 }
 
+static void *hyp_mc_alloc_gfp_fn(void *flags, unsigned long order)
+{
+	return (void *)__get_free_pages(*(gfp_t *)flags, order);
+}
+
 void free_hyp_memcache(struct kvm_hyp_memcache *mc)
 {
 	unsigned long flags = mc->flags;
@@ -1249,6 +1254,21 @@ int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages,
 				    kvm_host_pa, (void *)flags, order);
 }
 
+int topup_hyp_memcache_gfp(struct kvm_hyp_memcache *mc, unsigned long min_pages,
+			   unsigned long order, gfp_t gfp)
+{
+	void *flags = &gfp;
+
+	if (!is_protected_kvm_enabled())
+		return 0;
+
+	if (order > PAGE_SHIFT)
+		return -E2BIG;
+
+	return __topup_hyp_memcache(mc, min_pages, hyp_mc_alloc_gfp_fn,
+				    kvm_host_pa, flags, order);
+}
+
 /**
  * kvm_phys_addr_ioremap - map a device range to guest IPA
  *
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index e6df35aae840..0c45acbbff6e 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -1114,3 +1114,23 @@ unsigned long __pkvm_reclaim_hyp_alloc_mgt(unsigned long nr_pages)
 
 	return reclaimed;
 }
+
+int __pkvm_topup_hyp_alloc_mgt_gfp(unsigned long id, unsigned long nr_pages,
+				   unsigned long sz_alloc, gfp_t gfp)
+{
+	struct kvm_hyp_memcache mc;
+	int ret;
+
+	init_hyp_memcache(&mc);
+
+	ret = topup_hyp_memcache_gfp(&mc, nr_pages, get_order(sz_alloc), gfp);
+	if (ret)
+		return ret;
+
+	ret = kvm_call_hyp_nvhe(__pkvm_hyp_alloc_mgt_refill, id,
+				mc.head, mc.nr_pages);
+	if (ret)
+		free_hyp_memcache(&mc);
+
+	return ret;
+}
-- 
2.47.0.338.g60cca15819-goog