KVM: x86: do not go through ctxt->ops when emulating rsm

Now that RSM is implemented in a single emulator callback, there is no
point in going through other callbacks for the sake of modifying
processor state.  Just invoke KVM's own internal functions directly,
and remove the callbacks that were only used by em_rsm; the only
substantial difference is in the handling of the segment registers
and descriptor cache, which have to be parsed into a struct kvm_segment
instead of a struct desc_struct.

This also fixes a bug where emulator_set_segment was shifting the
limit left by 12 if the G bit is set, but the limit had not been
shifted right upon entry to SMM.

The emulator context is still used to restore EIP and the general
purpose registers.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220929172016.319443-5-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/kvm_emulate.h

@@ -116,16 +116,6 @@ struct x86_emulate_ops {
 			unsigned int bytes,
 			struct x86_exception *fault, bool system);
 
-	/*
-	 * read_phys: Read bytes of standard (non-emulated/special) memory.
-	 *            Used for descriptor reading.
-	 *  @addr:  [IN ] Physical address from which to read.
-	 *  @val:   [OUT] Value read from memory.
-	 *  @bytes: [IN ] Number of bytes to read from memory.
-	 */
-	int (*read_phys)(struct x86_emulate_ctxt *ctxt, unsigned long addr,
-			void *val, unsigned int bytes);
-
 	/*
 	 * write_std: Write bytes of standard (non-emulated/special) memory.
 	 *            Used for descriptor writing.
@@ -209,11 +199,8 @@ struct x86_emulate_ops {
 	int (*cpl)(struct x86_emulate_ctxt *ctxt);
 	void (*get_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong *dest);
 	int (*set_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong value);
-	u64 (*get_smbase)(struct x86_emulate_ctxt *ctxt);
-	void (*set_smbase)(struct x86_emulate_ctxt *ctxt, u64 smbase);
 	int (*set_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
 	int (*get_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
-	int (*set_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
 	int (*get_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
 	int (*check_pmc)(struct x86_emulate_ctxt *ctxt, u32 pmc);
 	int (*read_pmc)(struct x86_emulate_ctxt *ctxt, u32 pmc, u64 *pdata);

arch/x86/kvm/x86.c

@@ -7256,15 +7256,6 @@ static int emulator_read_std(struct x86_emulate_ctxt *ctxt,
 	return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, access, exception);
 }
 
-static int kvm_read_guest_phys_system(struct x86_emulate_ctxt *ctxt,
-		unsigned long addr, void *val, unsigned int bytes)
-{
-	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
-	int r = kvm_vcpu_read_guest(vcpu, addr, val, bytes);
-
-	return r < 0 ? X86EMUL_IO_NEEDED : X86EMUL_CONTINUE;
-}
-
 static int kvm_write_guest_virt_helper(gva_t addr, void *val, unsigned int bytes,
 				      struct kvm_vcpu *vcpu, u64 access,
 				      struct x86_exception *exception)
@@ -8056,26 +8047,6 @@ static int emulator_get_msr(struct x86_emulate_ctxt *ctxt,
 	return kvm_get_msr(emul_to_vcpu(ctxt), msr_index, pdata);
 }
 
-static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
-			    u32 msr_index, u64 data)
-{
-	return kvm_set_msr(emul_to_vcpu(ctxt), msr_index, data);
-}
-
-static u64 emulator_get_smbase(struct x86_emulate_ctxt *ctxt)
-{
-	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
-
-	return vcpu->arch.smbase;
-}
-
-static void emulator_set_smbase(struct x86_emulate_ctxt *ctxt, u64 smbase)
-{
-	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
-
-	vcpu->arch.smbase = smbase;
-}
-
 static int emulator_check_pmc(struct x86_emulate_ctxt *ctxt,
 			      u32 pmc)
 {
@@ -8174,7 +8145,6 @@ static const struct x86_emulate_ops emulate_ops = {
 	.write_gpr           = emulator_write_gpr,
 	.read_std            = emulator_read_std,
 	.write_std           = emulator_write_std,
-	.read_phys           = kvm_read_guest_phys_system,
 	.fetch               = kvm_fetch_guest_virt,
 	.read_emulated       = emulator_read_emulated,
 	.write_emulated      = emulator_write_emulated,
@@ -8194,11 +8164,8 @@ static const struct x86_emulate_ops emulate_ops = {
 	.cpl                 = emulator_get_cpl,
 	.get_dr              = emulator_get_dr,
 	.set_dr              = emulator_set_dr,
-	.get_smbase          = emulator_get_smbase,
-	.set_smbase          = emulator_set_smbase,
 	.set_msr_with_filter = emulator_set_msr_with_filter,
 	.get_msr_with_filter = emulator_get_msr_with_filter,
-	.set_msr             = emulator_set_msr,
 	.get_msr             = emulator_get_msr,
 	.check_pmc	     = emulator_check_pmc,
 	.read_pmc            = emulator_read_pmc,