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[11/12] KVM: PPC: Reduce reliance on analyse_instr() in mmio emulation

Message ID 20231201132618.555031-12-vaibhav@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series KVM: PPC: Nested APIv2 : Performance improvements | expand

Commit Message

Vaibhav Jain Dec. 1, 2023, 1:26 p.m. UTC 
From: Jordan Niethe <jniethe5@gmail.com>

Commit 709236039964 ("KVM: PPC: Reimplement non-SIMD LOAD/STORE
instruction mmio emulation with analyse_instr() input") and
commit 2b33cb585f94 ("KVM: PPC: Reimplement LOAD_FP/STORE_FP instruction
mmio emulation with analyse_instr() input") made
kvmppc_emulate_loadstore() use the results from analyse_instr() for
instruction emulation. In particular the effective address from
analyse_instr() is used for UPDATE type instructions and fact that
op.val is all ready endian corrected is used in the STORE case.

However, these changes now have some negative implications for the
nestedv2 case.  For analyse_instr() to determine the correct effective
address, the GPRs must be loaded from the L0. This is not needed as
vcpu->arch.vaddr_accessed is already set. Change back to using
vcpu->arch.vaddr_accessed.

In the STORE case, use kvmppc_get_gpr() value instead of the op.val.
kvmppc_get_gpr() will reload from the L0 if needed in the nestedv2 case.
This means if a byte reversal is needed must now be passed to
kvmppc_handle_store() like in the kvmppc_handle_load() case.

This means the call to kvmhv_nestedv2_reload_ptregs() can be avoided as
there is no concern about op.val being stale. Drop the call to
kvmhv_nestedv2_mark_dirty_ptregs() as without the call to
kvmhv_nestedv2_reload_ptregs(), stale state could be marked as valid.

This is fine as the required marking things dirty is already handled for
the UPDATE case by the call to kvmppc_set_gpr(). For LOADs, it is
handled in kvmppc_complete_mmio_load(). This is called either directly
in __kvmppc_handle_load() if the load can be handled in KVM, or on the
next kvm_arch_vcpu_ioctl_run() if an exit was required.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
 arch/powerpc/kvm/emulate_loadstore.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kvm/emulate_loadstore.c b/arch/powerpc/kvm/emulate_loadstore.c
index 077fd88a0b68..ec60c7979718 100644
--- a/arch/powerpc/kvm/emulate_loadstore.c
+++ b/arch/powerpc/kvm/emulate_loadstore.c
@@ -93,7 +93,6 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 
 	emulated = EMULATE_FAIL;
 	vcpu->arch.regs.msr = kvmppc_get_msr(vcpu);
-	kvmhv_nestedv2_reload_ptregs(vcpu, &vcpu->arch.regs);
 	if (analyse_instr(&op, &vcpu->arch.regs, inst) == 0) {
 		int type = op.type & INSTR_TYPE_MASK;
 		int size = GETSIZE(op.type);
@@ -112,7 +111,7 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 						op.reg, size, !instr_byte_swap);
 
 			if ((op.type & UPDATE) && (emulated != EMULATE_FAIL))
-				kvmppc_set_gpr(vcpu, op.update_reg, op.ea);
+				kvmppc_set_gpr(vcpu, op.update_reg, vcpu->arch.vaddr_accessed);
 
 			break;
 		}
@@ -132,7 +131,7 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 					     KVM_MMIO_REG_FPR|op.reg, size, 1);
 
 			if ((op.type & UPDATE) && (emulated != EMULATE_FAIL))
-				kvmppc_set_gpr(vcpu, op.update_reg, op.ea);
+				kvmppc_set_gpr(vcpu, op.update_reg, vcpu->arch.vaddr_accessed);
 
 			break;
 #endif
@@ -224,16 +223,17 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 			break;
 		}
 #endif
-		case STORE:
-			/* if need byte reverse, op.val has been reversed by
-			 * analyse_instr().
-			 */
-			emulated = kvmppc_handle_store(vcpu, op.val, size, 1);
+		case STORE: {
+			int instr_byte_swap = op.type & BYTEREV;
+
+			emulated = kvmppc_handle_store(vcpu, kvmppc_get_gpr(vcpu, op.reg),
+						       size, !instr_byte_swap);
 
 			if ((op.type & UPDATE) && (emulated != EMULATE_FAIL))
-				kvmppc_set_gpr(vcpu, op.update_reg, op.ea);
+				kvmppc_set_gpr(vcpu, op.update_reg, vcpu->arch.vaddr_accessed);
 
 			break;
+		}
 #ifdef CONFIG_PPC_FPU
 		case STORE_FP:
 			if (kvmppc_check_fp_disabled(vcpu))
@@ -254,7 +254,7 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 					kvmppc_get_fpr(vcpu, op.reg), size, 1);
 
 			if ((op.type & UPDATE) && (emulated != EMULATE_FAIL))
-				kvmppc_set_gpr(vcpu, op.update_reg, op.ea);
+				kvmppc_set_gpr(vcpu, op.update_reg, vcpu->arch.vaddr_accessed);
 
 			break;
 #endif
@@ -358,7 +358,6 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 	}
 
 	trace_kvm_ppc_instr(ppc_inst_val(inst), kvmppc_get_pc(vcpu), emulated);
-	kvmhv_nestedv2_mark_dirty_ptregs(vcpu, &vcpu->arch.regs);
 
 	/* Advance past emulated instruction. */
 	if (emulated != EMULATE_FAIL)