[v9,04/29] arm64: kvm: mte: Hide the MTE CPUID information from the guests

Commit Message

Catalin Marinas Sept. 4, 2020, 10:30 a.m. UTC

KVM does not support MTE in guests yet, so clear the corresponding field
in the ID_AA64PFR1_EL1 register. In addition, inject an undefined
exception in the guest if it accesses one of the GCR_EL1, RGSR_EL1,
TFSR_EL1 or TFSRE0_EL1 registers. While the emulate_sys_reg() function
already injects an undefined exception, this patch prevents the
unnecessary printk.

Signed-off-by: Catalin Marinas <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Cc: Steven Price <[e-mail]>
---

Notes:
    New in v9 (the ID register field hiding was moved here from an earlier
    patch).

 arch/arm64/kvm/sys_regs.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Comments

Marc Zyngier Sept. 4, 2020, 10:46 a.m. UTC | #1

On Fri, 04 Sep 2020 11:30:04 +0100,
Catalin Marinas <[e-mail]> wrote:
> 
> KVM does not support MTE in guests yet, so clear the corresponding field
> in the ID_AA64PFR1_EL1 register. In addition, inject an undefined
> exception in the guest if it accesses one of the GCR_EL1, RGSR_EL1,
> TFSR_EL1 or TFSRE0_EL1 registers. While the emulate_sys_reg() function
> already injects an undefined exception, this patch prevents the
> unnecessary printk.
> 
> Signed-off-by: Catalin Marinas <[e-mail]>
> Cc: Marc Zyngier <[e-mail]>
> Cc: Steven Price <[e-mail]>

Acked-by: Marc Zyngier <[e-mail]>

	M.

Patch

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 077293b5115f..379f4969d0bd 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1131,6 +1131,8 @@  static u64 read_id_reg(const struct kvm_vcpu *vcpu,
 		if (!vcpu_has_sve(vcpu))
 			val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT);
 		val &= ~(0xfUL << ID_AA64PFR0_AMU_SHIFT);
+	} else if (id == SYS_ID_AA64PFR1_EL1) {
+		val &= ~(0xfUL << ID_AA64PFR1_MTE_SHIFT);
 	} else if (id == SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) {
 		val &= ~((0xfUL << ID_AA64ISAR1_APA_SHIFT) |
 			 (0xfUL << ID_AA64ISAR1_API_SHIFT) |
@@ -1382,6 +1384,13 @@  static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	return true;
 }
 
+static bool access_mte_regs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
+			    const struct sys_reg_desc *r)
+{
+	kvm_inject_undefined(vcpu);
+	return false;
+}
+
 /* sys_reg_desc initialiser for known cpufeature ID registers */
 #define ID_SANITISED(name) {			\
 	SYS_DESC(SYS_##name),			\
@@ -1547,6 +1556,10 @@  static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_SCTLR_EL1), access_vm_reg, reset_val, SCTLR_EL1, 0x00C50078 },
 	{ SYS_DESC(SYS_ACTLR_EL1), access_actlr, reset_actlr, ACTLR_EL1 },
 	{ SYS_DESC(SYS_CPACR_EL1), NULL, reset_val, CPACR_EL1, 0 },
+
+	{ SYS_DESC(SYS_RGSR_EL1), access_mte_regs },
+	{ SYS_DESC(SYS_GCR_EL1), access_mte_regs },
+
 	{ SYS_DESC(SYS_ZCR_EL1), NULL, reset_val, ZCR_EL1, 0, .visibility = sve_visibility },
 	{ SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 },
 	{ SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 },
@@ -1571,6 +1584,9 @@  static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_ERXMISC0_EL1), trap_raz_wi },
 	{ SYS_DESC(SYS_ERXMISC1_EL1), trap_raz_wi },
 
+	{ SYS_DESC(SYS_TFSR_EL1), access_mte_regs },
+	{ SYS_DESC(SYS_TFSRE0_EL1), access_mte_regs },
+
 	{ SYS_DESC(SYS_FAR_EL1), access_vm_reg, reset_unknown, FAR_EL1 },
 	{ SYS_DESC(SYS_PAR_EL1), NULL, reset_unknown, PAR_EL1 },