[bug report] KVM: arm64: Add a range to __pkvm_host_unshare_guest()
Ben Horgan
ben.horgan at arm.com
Tue Jul 22 05:59:06 PDT 2025
Hi,
On trying to boot a pkvm guest when using transparent huge pages I see
the crash below. I'm using v6.6-rc7.
kvm [141]: nVHE hyp BUG at: arch/arm64/kvm/hyp/nvhe/mem_protect.c:1088!
It looks pkvm_pgtable_stage_relax_perms() can be called with a block
mapping but in __pkvm_host_relax_perms_guest() it assumes page size for
the assert_host_shared_guest() check. With the following patch, I no
longer see the crash:
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 8957734d6183..52c802da4172 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1010,9 +1010,12 @@ static int __check_host_shared_guest(struct
pkvm_hyp_vm *vm, u64 *__phys, u64 ip
return ret;
if (!kvm_pte_valid(pte))
return -ENOENT;
- if (kvm_granule_size(level) != size)
+ if (size && kvm_granule_size(level) != size)
return -E2BIG;
+ if (!size)
+ size = kvm_granule_size(level);
+
state = guest_get_page_state(pte, ipa);
if (state != PKVM_PAGE_SHARED_BORROWED)
return -EPERM;
@@ -1100,7 +1103,7 @@ int __pkvm_host_relax_perms_guest(u64 gfn, struct
pkvm_hyp_vcpu *vcpu, enum kvm_
if (prot & ~KVM_PGTABLE_PROT_RWX)
return -EINVAL;
- assert_host_shared_guest(vm, ipa, PAGE_SIZE);
+ assert_host_shared_guest(vm, ipa, 0);
guest_lock_component(vm);
ret = kvm_pgtable_stage2_relax_perms(&vm->pgt, ipa, prot, 0);
guest_unlock_component(vm);
root at 172:/# /share/lkvm run -k /share/arch/arm64/boot/Image
Info: # lkvm run -k /share/arch/arm64/boot/Image -m 704 -c 8 --name
guest-128
Info: Removed ghost socket file "/.lkvm//guest-128.sock".
[ 1406.521757] kvm [141]: nVHE hyp BUG at:
arch/arm64/kvm/hyp/nvhe/mem_protect.c:1088!
[ 1406.521804] kvm [141]: nVHE call trace:
[ 1406.521828] kvm [141]: [<ffff8000811676b4>]
__kvm_nvhe_hyp_panic+0xb4/0xe8
[ 1406.521946] kvm [141]: [<ffff80008116d12c>]
__kvm_nvhe_assert_host_shared_guest+0xb0/0x10c
[ 1406.522049] kvm [141]: [<ffff80008116f068>]
__kvm_nvhe___pkvm_host_relax_perms_guest+0x48/0x104
[ 1406.522157] kvm [141]: [<ffff800081169df8>]
__kvm_nvhe_handle___pkvm_host_relax_perms_guest+0x64/0x7c
[ 1406.522250] kvm [141]: [<ffff800081169f0c>]
__kvm_nvhe_handle_trap+0x8c/0x1a8
[ 1406.522333] kvm [141]: [<ffff8000811680fc>]
__kvm_nvhe___skip_pauth_save+0x4/0x4
[ 1406.522454] kvm [141]: ---[ end nVHE call trace ]---
[ 1406.522477] kvm [141]: Hyp Offset: 0xfffece8013600000
[ 1406.522554] Kernel panic - not syncing: HYP panic:
[ 1406.522554] PS:834003c9 PC:0000b1806db6d170 ESR:00000000f2000800
[ 1406.522554] FAR:ffff8000804be420 HPFAR:0000000000804be0
PAR:0000000000000000
[ 1406.522554] VCPU:0000000000000000
[ 1406.523337] CPU: 3 UID: 0 PID: 141 Comm: kvm-vcpu-0 Not tainted
6.16.0-rc7 #97 PREEMPT
[ 1406.523485] Hardware name: FVP Base RevC (DT)
[ 1406.523566] Call trace:
[ 1406.523629] show_stack+0x18/0x24 (C)
[ 1406.523753] dump_stack_lvl+0xd4/0x108
[ 1406.523899] dump_stack+0x18/0x24
[ 1406.524040] panic+0x3d8/0x448
[ 1406.524184] nvhe_hyp_panic_handler+0x10c/0x23c
[ 1406.524325] kvm_handle_guest_abort+0x68c/0x109c
[ 1406.524500] handle_exit+0x60/0x17c
[ 1406.524630] kvm_arch_vcpu_ioctl_run+0x2e0/0x8c0
[ 1406.524794] kvm_vcpu_ioctl+0x1a8/0x9cc
[ 1406.524919] __arm64_sys_ioctl+0xac/0x104
[ 1406.525067] invoke_syscall+0x48/0x10c
[ 1406.525189] el0_svc_common.constprop.0+0x40/0xe0
[ 1406.525322] do_el0_svc+0x1c/0x28
[ 1406.525441] el0_svc+0x38/0x120
[ 1406.525588] el0t_64_sync_handler+0x10c/0x138
[ 1406.525750] el0t_64_sync+0x1ac/0x1b0
[ 1406.525876] SMP: stopping secondary CPUs
[ 1406.525965] Kernel Offset: disabled
[ 1406.526032] CPU features: 0x0000,00000080,8e134ca1,9446773f
[ 1406.526130] Memory Limit: none
[ 1406.959099] ---[ end Kernel panic - not syncing: HYP panic:
[ 1406.959099] PS:834003c9 PC:0000b1806db6d170 ESR:00000000f2000800
[ 1406.959099] FAR:ffff8000804be420 HPFAR:0000000000804be0
PAR:0000000000000000
[ 1406.959099] VCPU:0000000000000000 ]---
Thanks,
Ben
More information about the linux-arm-kernel
mailing list