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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2020-11-26 12:02:06 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-11-27 11:14:27 -0500 |
| commit | 9a2a0d3ca163fc645991804b8b032f7d59326bb5 (patch) | |
| tree | ee7d81edd0ae37de9b7ac5e65c64ce3e79e42cee | |
| parent | 71cc849b7093bb83af966c0e60cb11b7f35cd746 (diff) | |
| download | linux-9a2a0d3ca163fc645991804b8b032f7d59326bb5.tar.bz2 | |
kvm: x86/mmu: Fix get_mmio_spte() on CPUs supporting 5-level PT
Commit 95fb5b0258b7 ("kvm: x86/mmu: Support MMIO in the TDP MMU") caused
the following WARNING on an Intel Ice Lake CPU:
get_mmio_spte: detect reserved bits on spte, addr 0xb80a0, dump hierarchy:
------ spte 0xb80a0 level 5.
------ spte 0xfcd210107 level 4.
------ spte 0x1004c40107 level 3.
------ spte 0x1004c41107 level 2.
------ spte 0x1db00000000b83b6 level 1.
WARNING: CPU: 109 PID: 10254 at arch/x86/kvm/mmu/mmu.c:3569 kvm_mmu_page_fault.cold.150+0x54/0x22f [kvm]
...
Call Trace:
? kvm_io_bus_get_first_dev+0x55/0x110 [kvm]
vcpu_enter_guest+0xaa1/0x16a0 [kvm]
? vmx_get_cs_db_l_bits+0x17/0x30 [kvm_intel]
? skip_emulated_instruction+0xaa/0x150 [kvm_intel]
kvm_arch_vcpu_ioctl_run+0xca/0x520 [kvm]
The guest triggering this crashes. Note, this happens with the traditional
MMU and EPT enabled, not with the newly introduced TDP MMU. Turns out,
there was a subtle change in the above mentioned commit. Previously,
walk_shadow_page_get_mmio_spte() was setting 'root' to 'iterator.level'
which is returned by shadow_walk_init() and this equals to
'vcpu->arch.mmu->shadow_root_level'. Now, get_mmio_spte() sets it to
'int root = vcpu->arch.mmu->root_level'.
The difference between 'root_level' and 'shadow_root_level' on CPUs
supporting 5-level page tables is that in some case we don't want to
use 5-level, in particular when 'cpuid_maxphyaddr(vcpu) <= 48'
kvm_mmu_get_tdp_level() returns '4'. In case upper layer is not used,
the corresponding SPTE will fail '__is_rsvd_bits_set()' check.
Revert to using 'shadow_root_level'.
Fixes: 95fb5b0258b7 ("kvm: x86/mmu: Support MMIO in the TDP MMU")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20201126110206.2118959-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 5bb1939b65d8..7a6ae9e90bd7 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3517,7 +3517,7 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) { u64 sptes[PT64_ROOT_MAX_LEVEL]; struct rsvd_bits_validate *rsvd_check; - int root = vcpu->arch.mmu->root_level; + int root = vcpu->arch.mmu->shadow_root_level; int leaf; int level; bool reserved = false; |