BACKPORT: OPENEULER: KVM: arm64: Fix missing traps of guest accesses to the MPAM registers

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T2RT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/snapshot/v6.7-rc2

---------------------------

commit 011e5f5 ("arm64/cpufeature: Add remaining feature bits in
ID_AA64PFR0 register") exposed the MPAM field of AA64PFR0_EL1 to guests,
but didn't add trap handling.

If you are unlucky, this results in an MPAM aware guest being delivered
an undef during boot. The host prints:
| kvm [97]: Unsupported guest sys_reg access at: ffff800080024c64 [00000005]
| { Op0( 3), Op1( 0), CRn(10), CRm( 5), Op2( 0), func_read },

Which results in:
| Internal error: Oops - Undefined instruction: 0000000002000000 [#1] PREEMPT SMP
| Modules linked in:
| CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.6.0-rc7-00559-gd89c186d50b2 #14616
| Hardware name: linux,dummy-virt (DT)
| pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : test_has_mpam+0x18/0x30
| lr : test_has_mpam+0x10/0x30
| sp : ffff80008000bd90
...
| Call trace:
|  test_has_mpam+0x18/0x30
|  update_cpu_capabilities+0x7c/0x11c
|  setup_cpu_features+0x14/0xd8
|  smp_cpus_done+0x24/0xb8
|  smp_init+0x7c/0x8c
|  kernel_init_freeable+0xf8/0x280
|  kernel_init+0x24/0x1e0
|  ret_from_fork+0x10/0x20
| Code: 910003fd 97ffffde 72001c0 5400008 (d538a500)
| ---[ end trace 0000000000000000 ]---
| Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
| ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

Add the support to enable the traps, and handle the three guest accessible
registers as RAZ/WI. This allows guests to keep the invariant id-register
value, while advertising that MPAM isn't really supported.

With MPAM v1.0 we can trap the MPAMIDR_EL1 register only if
ARM64_HAS_MPAM_HCR, with v1.1 an additional MPAM2_EL2.TIDR bit traps
MPAMIDR_EL1 on platforms that don't have MPAMHCR_EL2. Enable one of
these if either is supported. If neither is supported, the guest can
discover that the CPU has MPAM support, and how many PARTID etc the
host has ... but it can't influence anything, so its harmless.

Full support for the feature would only expose MPAM to the guest
if a psuedo-device has been created to describe the virt->phys partid
mapping the VMM expects. This will depend on ARM64_HAS_MPAM_HCR.

Fixes: 011e5f5 ("arm64/cpufeature: Add remaining feature bits in ID_AA64PFR0 register")
CC: Anshuman Khandual <[email protected]>
Link: https://lore.kernel.org/linux-arm-kernel/[email protected]/
Signed-off-by: James Morse <[email protected]>
Signed-off-by: Zeng Heng <[email protected]>

Link: https://gitee.com/openeuler/kernel/commit/c55eb641d53ac3d0a7ab9f1d1fae8a6460fc4f98
[Kexy: Dropped changes in arch/arm64/include/asm/kvm_arm.h,
 arch/arm64/kernel/image-vars.h,
 arch/arm64/kvm/hyp/include/hyp/switch.h, and arch/arm64/kvm/sys_regs.c]
Signed-off-by: Kexy Biscuit <[email protected]>

Author: James Morse

arch/arm64/include/asm/mpam.h

@@ -51,15 +51,15 @@
 DECLARE_STATIC_KEY_FALSE(arm64_mpam_has_hcr);
 
 /* check whether all CPUs have MPAM support */
-static inline bool mpam_cpus_have_feature(void)
+static __always_inline bool mpam_cpus_have_feature(void)
 {
 	if (IS_ENABLED(CONFIG_ARM64_MPAM))
 		return cpus_have_final_cap(ARM64_MPAM);
 	return false;
 }
 
 /* check whether all CPUs have MPAM virtualisation support */
-static inline bool mpam_cpus_have_mpam_hcr(void)
+static __always_inline bool mpam_cpus_have_mpam_hcr(void)
 {
 	if (IS_ENABLED(CONFIG_ARM64_MPAM))
 		return static_branch_unlikely(&arm64_mpam_has_hcr);