linux-kernel - [PATCH v2 1/7] KVM: arm64: Use visibility hook to treat ID regs as RAZ

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Message-Id: <20220902154804.1939819-2-oliver.upton@linux.dev>
Date:   Fri,  2 Sep 2022 15:47:57 +0000
From:   Oliver Upton <oliver.upton@...ux.dev>
To:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, Reiji Watanabe <reijiw@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/7] KVM: arm64: Use visibility hook to treat ID regs as RAZ

The generic id reg accessors already handle RAZ registers by way of the
visibility hook. Add a visibility hook that returns REG_RAZ
unconditionally and throw out the RAZ specific accessors.

Reviewed-by: Reiji Watanabe <reijiw@...gle.com>
Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
---
 arch/arm64/kvm/sys_regs.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 3234f50b8c4b..e18efb9211f0 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1145,6 +1145,12 @@ static unsigned int id_visibility(const struct kvm_vcpu *vcpu,
 	return 0;
 }
 
+static unsigned int raz_visibility(const struct kvm_vcpu *vcpu,
+				   const struct sys_reg_desc *r)
+{
+	return REG_RAZ;
+}
+
 /* cpufeature ID register access trap handlers */
 
 static bool __access_id_reg(struct kvm_vcpu *vcpu,
@@ -1168,13 +1174,6 @@ static bool access_id_reg(struct kvm_vcpu *vcpu,
 	return __access_id_reg(vcpu, p, r, raz);
 }
 
-static bool access_raz_id_reg(struct kvm_vcpu *vcpu,
-			      struct sys_reg_params *p,
-			      const struct sys_reg_desc *r)
-{
-	return __access_id_reg(vcpu, p, r, true);
-}
-
 /* Visibility overrides for SVE-specific control registers */
 static unsigned int sve_visibility(const struct kvm_vcpu *vcpu,
 				   const struct sys_reg_desc *rd)
@@ -1262,12 +1261,6 @@ static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 	return __set_id_reg(vcpu, rd, val, raz);
 }
 
-static int set_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
-			  u64 val)
-{
-	return __set_id_reg(vcpu, rd, val, true);
-}
-
 static int get_raz_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		       u64 *val)
 {
@@ -1374,9 +1367,10 @@ static unsigned int mte_visibility(const struct kvm_vcpu *vcpu,
  */
 #define ID_UNALLOCATED(crm, op2) {			\
 	Op0(3), Op1(0), CRn(0), CRm(crm), Op2(op2),	\
-	.access = access_raz_id_reg,			\
-	.get_user = get_raz_reg,			\
-	.set_user = set_raz_id_reg,			\
+	.access = access_id_reg,			\
+	.get_user = get_id_reg,				\
+	.set_user = set_id_reg,				\
+	.visibility = raz_visibility			\
 }
 
 /*
@@ -1386,9 +1380,10 @@ static unsigned int mte_visibility(const struct kvm_vcpu *vcpu,
  */
 #define ID_HIDDEN(name) {			\
 	SYS_DESC(SYS_##name),			\
-	.access = access_raz_id_reg,		\
-	.get_user = get_raz_reg,		\
-	.set_user = set_raz_id_reg,		\
+	.access = access_id_reg,		\
+	.get_user = get_id_reg,			\
+	.set_user = set_id_reg,			\
+	.visibility = raz_visibility,		\
 }
 
 /*
-- 
2.37.2.789.g6183377224-goog