linux-kernel - [PATCH v3 2/6] KVM: arm64: maintain per VM value for CTR

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Message-ID: <20240514072252.5657-3-sebott@redhat.com>
Date: Tue, 14 May 2024 09:22:48 +0200
From: Sebastian Ott <sebott@...hat.com>
To: linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>
Subject: [PATCH v3 2/6] KVM: arm64: maintain per VM value for CTR_EL0

In preparation for CTR_EL0 emulation maintain a per VM for this
register and use it where appropriate.

Signed-off-by: Sebastian Ott <sebott@...hat.com>
---
 arch/arm64/include/asm/kvm_host.h |  2 ++
 arch/arm64/kvm/sys_regs.c         | 21 ++++++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 212ae77eefaf..1259be5e2f3e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -331,6 +331,8 @@ struct kvm_arch {
 #define KVM_ARM_ID_REG_NUM	(IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1)
 	u64 id_regs[KVM_ARM_ID_REG_NUM];
 
+	u64 ctr_el0;
+
 	/* Masks for VNCR-baked sysregs */
 	struct kvm_sysreg_masks	*sysreg_masks;
 
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 41741bf4d2b2..0213c96f73f2 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -219,9 +219,9 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
  * Returns the minimum line size for the selected cache, expressed as
  * Log2(bytes).
  */
-static u8 get_min_cache_line_size(bool icache)
+static u8 get_min_cache_line_size(struct kvm *kvm, bool icache)
 {
-	u64 ctr = read_sanitised_ftr_reg(SYS_CTR_EL0);
+	u64 ctr = kvm->arch.ctr_el0;
 	u8 field;
 
 	if (icache)
@@ -248,7 +248,7 @@ static u32 get_ccsidr(struct kvm_vcpu *vcpu, u32 csselr)
 	if (vcpu->arch.ccsidr)
 		return vcpu->arch.ccsidr[csselr];
 
-	line_size = get_min_cache_line_size(csselr & CSSELR_EL1_InD);
+	line_size = get_min_cache_line_size(vcpu->kvm, csselr & CSSELR_EL1_InD);
 
 	/*
 	 * Fabricate a CCSIDR value as the overriding value does not exist.
@@ -283,7 +283,7 @@ static int set_ccsidr(struct kvm_vcpu *vcpu, u32 csselr, u32 val)
 	u32 i;
 
 	if ((val & CCSIDR_EL1_RES0) ||
-	    line_size < get_min_cache_line_size(csselr & CSSELR_EL1_InD))
+	    line_size < get_min_cache_line_size(vcpu->kvm, csselr & CSSELR_EL1_InD))
 		return -EINVAL;
 
 	if (!ccsidr) {
@@ -1886,7 +1886,7 @@ static bool access_ctr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	if (p->is_write)
 		return write_to_read_only(vcpu, p, r);
 
-	p->regval = read_sanitised_ftr_reg(SYS_CTR_EL0);
+	p->regval = vcpu->kvm->arch.ctr_el0;
 	return true;
 }
 
@@ -1906,7 +1906,7 @@ static bool access_clidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
  */
 static u64 reset_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
 {
-	u64 ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0);
+	u64 ctr_el0 = vcpu->kvm->arch.ctr_el0;
 	u64 clidr;
 	u8 loc;
 
@@ -1959,8 +1959,8 @@ static u64 reset_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
 static int set_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		      u64 val)
 {
-	u64 ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0);
 	u64 idc = !CLIDR_LOC(val) || (!CLIDR_LOUIS(val) && !CLIDR_LOUU(val));
+	u64 ctr_el0 = vcpu->kvm->arch.ctr_el0;
 
 	if ((val & CLIDR_EL1_RES0) || (!(ctr_el0 & CTR_EL0_IDC) && idc))
 		return -EINVAL;
@@ -3557,6 +3557,13 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
 	struct kvm *kvm = vcpu->kvm;
 	unsigned long i;
 
+	if (!kvm_vcpu_initialized(vcpu))
+		/*
+		 * Make sure CTR_EL0 is initialized before registers
+		 * that depend on it are reset.
+		 */
+		kvm->arch.ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0);
+
 	for (i = 0; i < ARRAY_SIZE(sys_reg_descs); i++) {
 		const struct sys_reg_desc *r = &sys_reg_descs[i];
 
-- 
2.42.0