From: Yan Zhao Date: Mon, 24 Feb 2025 07:10:39 +0000 (+0800) Subject: KVM: TDX: KVM: TDX: Always honor guest PAT on TDX enabled guests X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=90fe64a94d5475738ca5db781cdf93ab39bf844f;p=linux-2.6-microblaze.git KVM: TDX: KVM: TDX: Always honor guest PAT on TDX enabled guests Always honor guest PAT in KVM-managed EPTs on TDX enabled guests by making self-snoop feature a hard dependency for TDX and making quirk KVM_X86_QUIRK_IGNORE_GUEST_PAT not a valid quirk once TDX is enabled. The quirk KVM_X86_QUIRK_IGNORE_GUEST_PAT only affects memory type of KVM-managed EPTs. For the TDX-module-managed private EPT, memory type is always forced to WB now. Honoring guest PAT in KVM-managed EPTs ensures KVM does not invoke kvm_zap_gfn_range() when attaching/detaching non-coherent DMA devices, which would cause mirrored EPTs for TDs to be zapped, leading to the TDX-module-managed private EPT being incorrectly zapped. As a new feature, TDX always comes with support for self-snoop, and does not have to worry about unmodifiable but buggy guests. So, simply ignore KVM_X86_QUIRK_IGNORE_GUEST_PAT on TDX guests just like kvm-amd.ko already does. Suggested-by: Sean Christopherson Signed-off-by: Yan Zhao Message-ID: <20250224071039.31511-1-yan.y.zhao@intel.com> [Only apply to TDX guests. - Paolo] Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index db1ca8b22340..fb4f9aa84b95 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -625,6 +625,7 @@ int tdx_vm_init(struct kvm *kvm) kvm->arch.has_protected_state = true; kvm->arch.has_private_mem = true; + kvm->arch.disabled_quirks |= KVM_X86_QUIRK_IGNORE_GUEST_PAT; /* * Because guest TD is protected, VMM can't parse the instruction in TD. @@ -3475,6 +3476,11 @@ int __init tdx_bringup(void) goto success_disable_tdx; } + if (!cpu_feature_enabled(X86_FEATURE_SELFSNOOP)) { + pr_err("Self-snoop is required for TDX\n"); + goto success_disable_tdx; + } + if (!cpu_feature_enabled(X86_FEATURE_TDX_HOST_PLATFORM)) { pr_err("tdx: no TDX private KeyIDs available\n"); goto success_disable_tdx;