Re: [PATCH v2 2/2] KVM: s390: fix for hugepage vmalloc

From: Christian Borntraeger
Date: Tue Jun 08 2021 - 15:01:21 EST



On 08.06.21 20:06, Claudio Imbrenda wrote:
The Create Secure Configuration Ultravisor Call does not support using
large pages for the virtual memory area. This is a hardware limitation.

This patch replaces the vzalloc call with a longer but equivalent
__vmalloc_node_range call, also setting the VM_NO_HUGE_VMAP flag, to
guarantee that this allocation will not be performed with large pages.

Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Fixes: 121e6f3258fe393e22c3 ("mm/vmalloc: hugepage vmalloc mappings")
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>

Would be good to have this in 5.13, as for everything else we want to have
hugepages in vmalloc space on s390.

In case Andrew picks this up
Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
for the KVM/390 part.

---
arch/s390/kvm/pv.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 813b6e93dc83..6087fe7ae77c 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -140,7 +140,10 @@ static int kvm_s390_pv_alloc_vm(struct kvm *kvm)
/* Allocate variable storage */
vlen = ALIGN(virt * ((npages * PAGE_SIZE) / HPAGE_SIZE), PAGE_SIZE);
vlen += uv_info.guest_virt_base_stor_len;
- kvm->arch.pv.stor_var = vzalloc(vlen);
+ kvm->arch.pv.stor_var = __vmalloc_node_range(vlen, PAGE_SIZE, VMALLOC_START, VMALLOC_END,
+ GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL,
+ VM_NO_HUGE_VMAP, NUMA_NO_NODE,
+ __builtin_return_address(0));
if (!kvm->arch.pv.stor_var)
goto out_err;
return 0;