xen/arm: don't read aarch32 regs when aarch32 isn't available

Don't read aarch32 system registers at boot time when the aarch32 state
is not available at EL0. They are UNKNOWN, so it is not useful to read
them. Moreover, on Cavium ThunderX reading ID_PFR2_EL1 generates an
unsupported exception which causes a Xen crash.  Instead, only read them
when aarch32 is available.

Leave the corresponding fields in struct cpuinfo_arm so that they
are read-as-zero from a guest.

Since we are editing identify_cpu, also fix the indentation: 4 spaces
instead of 8.

Fixes: 9cfdb489af81 ("xen/arm: Add ID registers and complete cpuinfo")
Link: https://lore.kernel.org/xen-devel/f90e40ee-b042-6cc5-a08d-aef41a279527@suse.com/
Suggested-by: Julien Grall <julien@xen.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>

diff --git a/xen/arch/arm/cpufeature.c b/xen/arch/arm/cpufeature.c
index 698bfa02013925f17d3f2c090b4d8dd77fc198ec..99fe4db2806348552d672cf8beb669ddbd184443 100644 (file)
--- a/xen/arch/arm/cpufeature.c
+++ b/xen/arch/arm/cpufeature.c
@@ -101,29 +101,35 @@ int enable_nonboot_cpu_caps(const struct arm_cpu_capabilities *caps)
 
 void identify_cpu(struct cpuinfo_arm *c)
 {
-        c->midr.bits = READ_SYSREG(MIDR_EL1);
-        c->mpidr.bits = READ_SYSREG(MPIDR_EL1);
+    bool aarch32_el0 = true;
+
+    c->midr.bits = READ_SYSREG(MIDR_EL1);
+    c->mpidr.bits = READ_SYSREG(MPIDR_EL1);
 
 #ifdef CONFIG_ARM_64
-        c->pfr64.bits[0] = READ_SYSREG(ID_AA64PFR0_EL1);
-        c->pfr64.bits[1] = READ_SYSREG(ID_AA64PFR1_EL1);
+    c->pfr64.bits[0] = READ_SYSREG(ID_AA64PFR0_EL1);
+    c->pfr64.bits[1] = READ_SYSREG(ID_AA64PFR1_EL1);
+
+    c->dbg64.bits[0] = READ_SYSREG(ID_AA64DFR0_EL1);
+    c->dbg64.bits[1] = READ_SYSREG(ID_AA64DFR1_EL1);
 
-        c->dbg64.bits[0] = READ_SYSREG(ID_AA64DFR0_EL1);
-        c->dbg64.bits[1] = READ_SYSREG(ID_AA64DFR1_EL1);
+    c->aux64.bits[0] = READ_SYSREG(ID_AA64AFR0_EL1);
+    c->aux64.bits[1] = READ_SYSREG(ID_AA64AFR1_EL1);
 
-        c->aux64.bits[0] = READ_SYSREG(ID_AA64AFR0_EL1);
-        c->aux64.bits[1] = READ_SYSREG(ID_AA64AFR1_EL1);
+    c->mm64.bits[0]  = READ_SYSREG(ID_AA64MMFR0_EL1);
+    c->mm64.bits[1]  = READ_SYSREG(ID_AA64MMFR1_EL1);
+    c->mm64.bits[2]  = READ_SYSREG(ID_AA64MMFR2_EL1);
 
-        c->mm64.bits[0]  = READ_SYSREG(ID_AA64MMFR0_EL1);
-        c->mm64.bits[1]  = READ_SYSREG(ID_AA64MMFR1_EL1);
-        c->mm64.bits[2]  = READ_SYSREG(ID_AA64MMFR2_EL1);
+    c->isa64.bits[0] = READ_SYSREG(ID_AA64ISAR0_EL1);
+    c->isa64.bits[1] = READ_SYSREG(ID_AA64ISAR1_EL1);
 
-        c->isa64.bits[0] = READ_SYSREG(ID_AA64ISAR0_EL1);
-        c->isa64.bits[1] = READ_SYSREG(ID_AA64ISAR1_EL1);
+    c->zfr64.bits[0] = READ_SYSREG(ID_AA64ZFR0_EL1);
 
-        c->zfr64.bits[0] = READ_SYSREG(ID_AA64ZFR0_EL1);
+    aarch32_el0 = cpu_feature64_has_el0_32(c);
 #endif
 
+    if ( aarch32_el0 )
+    {
         c->pfr32.bits[0] = READ_SYSREG(ID_PFR0_EL1);
         c->pfr32.bits[1] = READ_SYSREG(ID_PFR1_EL1);
         c->pfr32.bits[2] = READ_SYSREG(ID_PFR2_EL1);
@@ -153,6 +159,7 @@ void identify_cpu(struct cpuinfo_arm *c)
 #ifndef MVFR2_MAYBE_UNDEFINED
         c->mvfr.bits[2] = READ_SYSREG(MVFR2_EL1);
 #endif
+    }
 }
 
 /*

diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index 6058744c185c908c2718d6c783fede37c71348b4..13a2739a69b8e601caaf4290cd931ee0214e3412 100644 (file)
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -5,6 +5,8 @@
 #define cpu_feature64(c, feat)         ((c)->pfr64.feat)
 #define boot_cpu_feature64(feat)       (boot_cpu_data.pfr64.feat)
 
+#define cpu_feature64_has_el0_32(c)    (cpu_feature64(c, el0) == 2)
+
 #define cpu_has_el0_32    (boot_cpu_feature64(el0) == 2)
 #define cpu_has_el0_64    (boot_cpu_feature64(el0) >= 1)
 #define cpu_has_el1_32    (boot_cpu_feature64(el1) == 2)