4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sean Christopherson sean.j.christopherson@intel.com
commit 35be0aded76b54a24dc8aa678a71bca22273e8d8 upstream.
Re-execution after an emulation decode failure is only intended to handle a case where two or vCPUs race to write a shadowed page, i.e. we should never re-execute an instruction as part of RSM emulation.
Add a new helper, kvm_emulate_instruction_from_buffer(), to support emulating from a pre-defined buffer. This eliminates the last direct call to x86_emulate_instruction() outside of kvm_mmu_page_fault(), which means x86_emulate_instruction() can be unexported in a future patch.
Fixes: 7607b7174405 ("KVM: SVM: install RSM intercept") Cc: Brijesh Singh brijesh.singh@amd.com Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com Cc: stable@vger.kernel.org Signed-off-by: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/kvm_host.h | 7 +++++++ arch/x86/kvm/svm.c | 4 ++-- 2 files changed, 9 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1212,6 +1212,13 @@ static inline int emulate_instruction(st emulation_type | EMULTYPE_NO_REEXECUTE, NULL, 0); }
+static inline int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu, + void *insn, int insn_len) +{ + return x86_emulate_instruction(vcpu, 0, EMULTYPE_NO_REEXECUTE, + insn, insn_len); +} + void kvm_enable_efer_bits(u64); bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer); int kvm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr); --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -3875,8 +3875,8 @@ static int emulate_on_interception(struc
static int rsm_interception(struct vcpu_svm *svm) { - return x86_emulate_instruction(&svm->vcpu, 0, 0, - rsm_ins_bytes, 2) == EMULATE_DONE; + return kvm_emulate_instruction_from_buffer(&svm->vcpu, + rsm_ins_bytes, 2) == EMULATE_DONE; }
static int rdpmc_interception(struct vcpu_svm *svm)