From:   Kautuk Consul <kconsul@linux.vnet.ibm.com>
To:     Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
        Sathvika Vasireddy <sv@linux.ibm.com>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        Fabiano Rosas <farosas@linux.ibm.com>
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Kautuk Consul <kconsul@linux.vnet.ibm.com>
Subject: [PATCH v2 2/2] arch/powerpc/kvm: kvmppc_hv_entry: remove r4 argument
Date:   Mon,  6 Mar 2023 07:37:40 -0500
Message-Id: <20230306123740.3648841-3-kconsul@linux.vnet.ibm.com>
In-Reply-To: <20230306123740.3648841-1-kconsul@linux.vnet.ibm.com>
References: <20230306123740.3648841-1-kconsul@linux.vnet.ibm.com>
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kvmppc_hv_entry is called from only 2 locations within
book3s_hv_rmhandlers.S. Both of those locations set r4
as HSTATE_KVM_VCPU(r13) before calling kvmppc_hv_entry.
So, shift the r4 load instruction to kvmppc_hv_entry and
thus modify the calling convention of this function.

Signed-off-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index b81ba4ee0521..da9a15db12fe 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -85,7 +85,7 @@ _GLOBAL_TOC(kvmppc_hv_entry_trampoline)
 	RFI_TO_KERNEL
 
 kvmppc_call_hv_entry:
-	ld	r4, HSTATE_KVM_VCPU(r13)
+	/* Enter guest. */
 	bl	kvmppc_hv_entry
 
 	/* Back from guest - restore host state and return to caller */
@@ -352,9 +352,7 @@ kvm_secondary_got_guest:
 	mtspr	SPRN_LDBAR, r0
 	isync
 63:
-	/* Order load of vcpu after load of vcore */
-	lwsync
-	ld	r4, HSTATE_KVM_VCPU(r13)
+	/* Enter guest. */
 	bl	kvmppc_hv_entry
 
 	/* Back from the guest, go back to nap */
@@ -506,7 +504,6 @@ SYM_INNER_LABEL(kvmppc_hv_entry, SYM_L_LOCAL)
 
 	/* Required state:
 	 *
-	 * R4 = vcpu pointer (or NULL)
 	 * MSR = ~IR|DR
 	 * R13 = PACA
 	 * R1 = host R1
@@ -524,6 +521,8 @@ SYM_INNER_LABEL(kvmppc_hv_entry, SYM_L_LOCAL)
 	li	r6, KVM_GUEST_MODE_HOST_HV
 	stb	r6, HSTATE_IN_GUEST(r13)
 
+	ld	r4, HSTATE_KVM_VCPU(r13)
+
 #ifdef CONFIG_KVM_BOOK3S_HV_P8_TIMING
 	/* Store initial timestamp */
 	cmpdi	r4, 0
-- 
2.36.1