[v2,5/9] KVM: x86: Set kvm_x86_ops only after ->hardware_setup() completes
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Message ID 20200218235437.20533-6-sean.j.christopherson@intel.com
State Not Applicable
Headers show
Series
  • KVM: Move x86 init ops to separate struct
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Commit Message

Sean Christopherson Feb. 18, 2020, 11:54 p.m. UTC
Set kvm_x86_ops with the vendor's ops only after ->hardware_setup()
completes to "prevent" using kvm_x86_ops before they are ready, i.e. to
generate a null pointer fault instead of silently consuming unconfigured
state.

An alternative implementation would be to have ->hardware_setup()
return the vendor's ops, but that would require non-trivial refactoring,
and would arguably result in less readable code, e.g. ->hardware_setup()
would need to use ERR_PTR() in multiple locations, and each vendor's
declaration of the runtime ops would be less obvious.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/x86.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 315297dec85c..bffd1f703f8e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7335,8 +7335,6 @@  int kvm_arch_init(void *opaque)
 	if (r)
 		goto out_free_percpu;
 
-	kvm_x86_ops = ops->runtime_ops;
-
 	kvm_mmu_set_mask_ptes(PT_USER_MASK, PT_ACCESSED_MASK,
 			PT_DIRTY_MASK, PT64_NX_MASK, 0,
 			PT_PRESENT_MASK, 0, sme_me_mask);
@@ -9600,6 +9598,8 @@  int kvm_arch_hardware_setup(void *opaque)
 	if (r != 0)
 		return r;
 
+	kvm_x86_ops = ops->runtime_ops;
+
 	cr4_reserved_bits = kvm_host_cr4_reserved_bits(&boot_cpu_data);
 
 	if (kvm_has_tsc_control) {