| Date | Tue, 5 Apr 2022 17:25:34 +0200 | Subject | Re: [RFC PATCH v5 042/104] KVM: x86/mmu: Track shadow MMIO value/mask on a per-VM basis | From | Paolo Bonzini <> |
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On 3/4/22 20:48, isaku.yamahata@intel.com wrote: > + if (enable_ept) { > + const u64 init_value = enable_tdx ? VMX_EPT_SUPPRESS_VE_BIT : 0ull; > kvm_mmu_set_ept_masks(enable_ept_ad_bits, > - cpu_has_vmx_ept_execute_only()); > + cpu_has_vmx_ept_execute_only(), init_value); > + kvm_mmu_set_spte_init_value(init_value); > + }
I think kvm-intel.ko should use VMX_EPT_SUPPRESS_VE_BIT unconditionally as the init value. The bit is ignored anyway if the "EPT-violation #VE" execution control is 0. Otherwise looks good, but I have a couple more crazy ideas:
1) there could even be a test mode where KVM enables the execution control, traps #VE in the exception bitmap, and shouts loudly if it gets a #VE. That might avoid hard-to-find bugs due to forgetting about VMX_EPT_SUPPRESS_VE_BIT.
2) or even, perhaps the init_value for the TDP MMU could set bit 63 _unconditionally_, because KVM always sets the NX bit on AMD hardware. That would remove the whole infrastructure to keep shadow_init_value, because it would be constant 0 in mmu.c and constant BIT(63) in tdp_mmu.c.
Sean, what do you think?
Paolo
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