Commit 1a61bd0d authored by Yang Weijiang's avatar Yang Weijiang Committed by Sean Christopherson
Browse files

KVM: x86: Save and reload SSP to/from SMRAM 



Save CET SSP to SMRAM on SMI and reload it on RSM. KVM emulates HW arch
behavior when guest enters/leaves SMM mode,i.e., save registers to SMRAM
at the entry of SMM and reload them at the exit to SMM. Per SDM, SSP is
one of such registers on 64-bit Arch, and add the support for SSP.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarYang Weijiang <weijiang.yang@intel.com>
Tested-by: default avatarMathias Krause <minipli@grsecurity.net>
Tested-by: default avatarJohn Allen <john.allen@amd.com>
Tested-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: default avatarChao Gao <chao.gao@intel.com>
Reviewed-by: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-16-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 8b59d027

arch/x86/kvm/smm.c

+8 −0
Original line number Diff line number Diff line
@@ -269,6 +269,10 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, 
	enter_smm_save_seg_64(vcpu, &smram->gs, VCPU_SREG_GS);



	smram->int_shadow = kvm_x86_call(get_interrupt_shadow)(vcpu);



	if (guest_cpu_cap_has(vcpu, X86_FEATURE_SHSTK) &&

	    kvm_msr_read(vcpu, MSR_KVM_INTERNAL_GUEST_SSP, &smram->ssp))

		kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);

}

#endif
@@ -558,6 +562,10 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt, 
	kvm_x86_call(set_interrupt_shadow)(vcpu, 0);

	ctxt->interruptibility = (u8)smstate->int_shadow;



	if (guest_cpu_cap_has(vcpu, X86_FEATURE_SHSTK) &&

	    kvm_msr_write(vcpu, MSR_KVM_INTERNAL_GUEST_SSP, smstate->ssp))

		return X86EMUL_UNHANDLEABLE;



	return X86EMUL_CONTINUE;

}

#endif

arch/x86/kvm/smm.h

+1 −1
Original line number Diff line number Diff line
@@ -116,8 +116,8 @@ struct kvm_smram_state_64 { 
	u32 smbase;

	u32 reserved4[5];



	/* ssp and svm_* fields below are not implemented by KVM */

	u64 ssp;

	/* svm_* fields below are not implemented by KVM */

	u64 svm_guest_pat;

	u64 svm_host_efer;

	u64 svm_host_cr4;