[PATCH 5/5] KVM: arm64: Handle AArch32 SPSR_{irq,abt,und,fiq} as RAZ/WI

Marc Zyngier
2023-10-23T09:55:40Z

When trapping accesses from a NV guest that tries to access
SPSR_{irq,abt,und,fiq}, make sure we handle them as RAZ/WI,
as if AArch32 wasn't implemented.

This involves a bit of repainting to make the visibility
handler more generic.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/sysreg.h | 4 ++++
arch/arm64/kvm/sys_regs.c | 16 +++++++++++++---
2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 4a20a7dc5bc4..5e65f51c10d2 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -505,6 +505,10 @@
#define SYS_SPSR_EL2 sys_reg(3, 4, 4, 0, 0)
#define SYS_ELR_EL2 sys_reg(3, 4, 4, 0, 1)
#define SYS_SP_EL1 sys_reg(3, 4, 4, 1, 0)
+#define SYS_SPSR_irq sys_reg(3, 4, 4, 3, 0)
+#define SYS_SPSR_abt sys_reg(3, 4, 4, 3, 1)
+#define SYS_SPSR_und sys_reg(3, 4, 4, 3, 2)
+#define SYS_SPSR_fiq sys_reg(3, 4, 4, 3, 3)
#define SYS_IFSR32_EL2 sys_reg(3, 4, 5, 0, 1)
#define SYS_AFSR0_EL2 sys_reg(3, 4, 5, 1, 0)
#define SYS_AFSR1_EL2 sys_reg(3, 4, 5, 1, 1)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 0071ccccaf00..be1ebd2c5ba0 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1791,8 +1791,8 @@ static unsigned int el2_visibility(const struct kvm_vcpu *vcpu,
* HCR_EL2.E2H==1, and only in the sysreg table for convenience of
* handling traps. Given that, they are always hidden from userspace.
*/
-static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu,
- const struct sys_reg_desc *rd)
+static unsigned int hidden_user_visibility(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
{
return REG_HIDDEN_USER;
}
@@ -1803,7 +1803,7 @@ static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu,
.reset = rst, \
.reg = name##_EL1, \
.val = v, \
- .visibility = elx2_visibility, \
+ .visibility = hidden_user_visibility, \
}

/*
@@ -2387,6 +2387,16 @@ static const struct sys_reg_desc sys_reg_descs[] = {
EL2_REG(ELR_EL2, access_rw, reset_val, 0),
{ SYS_DESC(SYS_SP_EL1), access_sp_el1},

+ /* AArch32 SPSR_* are RES0 if trapped from a NV guest */
+ { SYS_DESC(SYS_SPSR_irq), .access = trap_raz_wi,
+ .visibility = hidden_user_visibility },
+ { SYS_DESC(SYS_SPSR_abt), .access = trap_raz_wi,
+ .visibility = hidden_user_visibility },
+ { SYS_DESC(SYS_SPSR_und), .access = trap_raz_wi,
+ .visibility = hidden_user_visibility },
+ { SYS_DESC(SYS_SPSR_fiq), .access = trap_raz_wi,
+ .visibility = hidden_user_visibility },
+
{ SYS_DESC(SYS_IFSR32_EL2), trap_undef, reset_unknown, IFSR32_EL2 },
EL2_REG(AFSR0_EL2, access_rw, reset_val, 0),
EL2_REG(AFSR1_EL2, access_rw, reset_val, 0),
--
2.39.2