Revert "KVM: arm64: Snapshot all non-zero RES0/RES1 sysreg fields for later checking"

This reverts commits 99101dda29e3186b1356b0dc4dbb835c02c71ac9 and
b80b701d5a67d07f4df4a21e09cb31f6bc1feeca.

Linus reports that the sysreg reserved bit checks in KVM have led to
build failures, arising from commit fdd867fe9b32 ("arm64/sysreg: Add
register fields for ID_AA64DFR1_EL1") giving meaning to fields that were
previously RES0.

Of course, this is a genuine issue, since KVM's sysreg emulation depends
heavily on the definition of reserved fields. But at this point the
build breakage is far more offensive, and the right course of action is
to revert and retry later.

All of these build-time assertions were on by default before
commit 99101dda29e3 ("KVM: arm64: Make build-time check of RES0/RES1
bits optional"), so deliberately revert it all atomically to avoid
introducing further breakage of bisection.

Link: https://lore.kernel.org/all/CAHk-=whCvkhc8BbFOUf1ddOsgSGgEjwoKv77=HEY1UiVCydGqw@mail.gmail.com/
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 937f15b7d8c3034dd97dc1ed7230b8cefdaa34a0..58f09370d17e017614c690000f55e9b3b816d77c 100644 (file)
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -65,15 +65,4 @@ config PROTECTED_NVHE_STACKTRACE
 
          If unsure, or not using protected nVHE (pKVM), say N.
 
-config KVM_ARM64_RES_BITS_PARANOIA
-       bool "Build-time check of RES0/RES1 bits"
-       depends on KVM
-       default n
-       help
-         Say Y here to validate that KVM's knowledge of most system
-         registers' RES0/RES1 bits matches when the rest of the kernel
-         defines. Expect the build to fail badly if you enable this.
-
-         Just say N.
-
 endif # VIRTUALIZATION

diff --git a/arch/arm64/kvm/check-res-bits.h b/arch/arm64/kvm/check-res-bits.h
deleted file mode 100644 (file)
index 2d98e60..0000000
--- a/arch/arm64/kvm/check-res-bits.h
+++ /dev/null
@@ -1,125 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) 2024 - Google LLC
- * Author: Marc Zyngier <maz@kernel.org>
- */
-
-#include <asm/sysreg-defs.h>
-
-/*
- * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
- *
- * If any of these BUILD_BUG_ON() fails, that's because some bits that
- * were reserved have gained some other meaning, and KVM needs to know
- * about those.
- *
- * In such case, do *NOT* blindly change the assertion so that it
- * passes, but also teach the rest of the code about the actual
- * change.
- *
- * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
- */
-static inline void check_res_bits(void)
-{
-#ifdef CONFIG_KVM_ARM64_RES_BITS_PARANOIA
-
-       BUILD_BUG_ON(OSDTRRX_EL1_RES0           != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(MDCCINT_EL1_RES0           != (GENMASK_ULL(63, 31) | GENMASK_ULL(28, 0)));
-       BUILD_BUG_ON(MDSCR_EL1_RES0             != (GENMASK_ULL(63, 36) | GENMASK_ULL(28, 28) | GENMASK_ULL(25, 24) | GENMASK_ULL(20, 20) | GENMASK_ULL(18, 16) | GENMASK_ULL(11, 7) | GENMASK_ULL(5, 1)));
-       BUILD_BUG_ON(OSDTRTX_EL1_RES0           != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(OSECCR_EL1_RES0            != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(OSLAR_EL1_RES0             != (GENMASK_ULL(63, 1)));
-       BUILD_BUG_ON(ID_PFR0_EL1_RES0           != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_PFR1_EL1_RES0           != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_DFR0_EL1_RES0           != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_AFR0_EL1_RES0           != (GENMASK_ULL(63, 16)));
-       BUILD_BUG_ON(ID_MMFR0_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_MMFR1_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_MMFR2_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_MMFR3_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_ISAR0_EL1_RES0          != (GENMASK_ULL(63, 28)));
-       BUILD_BUG_ON(ID_ISAR1_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_ISAR2_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_ISAR3_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_ISAR4_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_ISAR5_EL1_RES0          != (GENMASK_ULL(63, 32) | GENMASK_ULL(23, 20)));
-       BUILD_BUG_ON(ID_ISAR6_EL1_RES0          != (GENMASK_ULL(63, 28)));
-       BUILD_BUG_ON(ID_MMFR4_EL1_RES0          != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(MVFR0_EL1_RES0             != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(MVFR1_EL1_RES0             != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(MVFR2_EL1_RES0             != (GENMASK_ULL(63, 8)));
-       BUILD_BUG_ON(ID_PFR2_EL1_RES0           != (GENMASK_ULL(63, 12)));
-       BUILD_BUG_ON(ID_DFR1_EL1_RES0           != (GENMASK_ULL(63, 8)));
-       BUILD_BUG_ON(ID_MMFR5_EL1_RES0          != (GENMASK_ULL(63, 8)));
-       BUILD_BUG_ON(ID_AA64PFR1_EL1_RES0       != (GENMASK_ULL(23, 20)));
-       BUILD_BUG_ON(ID_AA64PFR2_EL1_RES0       != (GENMASK_ULL(63, 36) | GENMASK_ULL(31, 12)));
-       BUILD_BUG_ON(ID_AA64ZFR0_EL1_RES0       != (GENMASK_ULL(63, 60) | GENMASK_ULL(51, 48) | GENMASK_ULL(39, 36) | GENMASK_ULL(31, 28) | GENMASK_ULL(15, 8)));
-       BUILD_BUG_ON(ID_AA64SMFR0_EL1_RES0      != (GENMASK_ULL(62, 61) | GENMASK_ULL(51, 49) | GENMASK_ULL(31, 31) | GENMASK_ULL(27, 0)));
-       BUILD_BUG_ON(ID_AA64FPFR0_EL1_RES0      != (GENMASK_ULL(63, 32) | GENMASK_ULL(27, 2)));
-       BUILD_BUG_ON(ID_AA64DFR0_EL1_RES0       != (GENMASK_ULL(27, 24) | GENMASK_ULL(19, 16)));
-       BUILD_BUG_ON(ID_AA64DFR1_EL1_RES0       != (GENMASK_ULL(63, 0)));
-       BUILD_BUG_ON(ID_AA64AFR0_EL1_RES0       != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(ID_AA64AFR1_EL1_RES0       != (GENMASK_ULL(63, 0)));
-       BUILD_BUG_ON(ID_AA64ISAR0_EL1_RES0      != (GENMASK_ULL(3, 0)));
-       BUILD_BUG_ON(ID_AA64ISAR2_EL1_RES0      != (GENMASK_ULL(47, 44)));
-       BUILD_BUG_ON(ID_AA64ISAR3_EL1_RES0      != (GENMASK_ULL(63, 16)));
-       BUILD_BUG_ON(ID_AA64MMFR0_EL1_RES0      != (GENMASK_ULL(55, 48)));
-       BUILD_BUG_ON(ID_AA64MMFR2_EL1_RES0      != (GENMASK_ULL(47, 44)));
-       BUILD_BUG_ON(ID_AA64MMFR3_EL1_RES0      != (GENMASK_ULL(51, 48)));
-       BUILD_BUG_ON(ID_AA64MMFR4_EL1_RES0      != (GENMASK_ULL(63, 40) | GENMASK_ULL(35, 28) | GENMASK_ULL(3, 0)));
-       BUILD_BUG_ON(SCTLR_EL1_RES0             != (GENMASK_ULL(17, 17)));
-       BUILD_BUG_ON(CPACR_ELx_RES0             != (GENMASK_ULL(63, 30) | GENMASK_ULL(27, 26) | GENMASK_ULL(23, 22) | GENMASK_ULL(19, 18) | GENMASK_ULL(15, 0)));
-       BUILD_BUG_ON(SMPRI_EL1_RES0             != (GENMASK_ULL(63, 4)));
-       BUILD_BUG_ON(ZCR_ELx_RES0               != (GENMASK_ULL(63, 9)));
-       BUILD_BUG_ON(SMCR_ELx_RES0              != (GENMASK_ULL(63, 32) | GENMASK_ULL(29, 9)));
-       BUILD_BUG_ON(GCSCR_ELx_RES0             != (GENMASK_ULL(63, 10) | GENMASK_ULL(7, 7) | GENMASK_ULL(4, 1)));
-       BUILD_BUG_ON(GCSPR_ELx_RES0             != (GENMASK_ULL(2, 0)));
-       BUILD_BUG_ON(GCSCRE0_EL1_RES0           != (GENMASK_ULL(63, 11) | GENMASK_ULL(7, 6) | GENMASK_ULL(4, 1)));
-       BUILD_BUG_ON(ALLINT_RES0                != (GENMASK_ULL(63, 14) | GENMASK_ULL(12, 0)));
-       BUILD_BUG_ON(PMSCR_EL1_RES0             != (GENMASK_ULL(63, 8) | GENMASK_ULL(2, 2)));
-       BUILD_BUG_ON(PMSICR_EL1_RES0            != (GENMASK_ULL(55, 32)));
-       BUILD_BUG_ON(PMSIRR_EL1_RES0            != (GENMASK_ULL(63, 32) | GENMASK_ULL(7, 1)));
-       BUILD_BUG_ON(PMSFCR_EL1_RES0            != (GENMASK_ULL(63, 19) | GENMASK_ULL(15, 4)));
-       BUILD_BUG_ON(PMSLATFR_EL1_RES0          != (GENMASK_ULL(63, 16)));
-       BUILD_BUG_ON(PMSIDR_EL1_RES0            != (GENMASK_ULL(63, 25) | GENMASK_ULL(7, 7)));
-       BUILD_BUG_ON(PMBLIMITR_EL1_RES0         != (GENMASK_ULL(11, 6) | GENMASK_ULL(4, 3)));
-       BUILD_BUG_ON(PMBSR_EL1_RES0             != (GENMASK_ULL(63, 32) | GENMASK_ULL(25, 20)));
-       BUILD_BUG_ON(PMBIDR_EL1_RES0            != (GENMASK_ULL(63, 12) | GENMASK_ULL(7, 6)));
-       BUILD_BUG_ON(CONTEXTIDR_ELx_RES0        != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(CCSIDR_EL1_RES0            != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(CLIDR_EL1_RES0             != (GENMASK_ULL(63, 47)));
-       BUILD_BUG_ON(CCSIDR2_EL1_RES0           != (GENMASK_ULL(63, 24)));
-       BUILD_BUG_ON(GMID_EL1_RES0              != (GENMASK_ULL(63, 4)));
-       BUILD_BUG_ON(SMIDR_EL1_RES0             != (GENMASK_ULL(63, 32) | GENMASK_ULL(14, 12)));
-       BUILD_BUG_ON(CSSELR_EL1_RES0            != (GENMASK_ULL(63, 5)));
-       BUILD_BUG_ON(CTR_EL0_RES0               != (GENMASK_ULL(63, 38) | GENMASK_ULL(30, 30) | GENMASK_ULL(13, 4)));
-       BUILD_BUG_ON(CTR_EL0_RES1               != (GENMASK_ULL(31, 31)));
-       BUILD_BUG_ON(DCZID_EL0_RES0             != (GENMASK_ULL(63, 5)));
-       BUILD_BUG_ON(SVCR_RES0                  != (GENMASK_ULL(63, 2)));
-       BUILD_BUG_ON(FPMR_RES0                  != (GENMASK_ULL(63, 38) | GENMASK_ULL(23, 23) | GENMASK_ULL(13, 9)));
-       BUILD_BUG_ON(HFGxTR_EL2_RES0            != (GENMASK_ULL(51, 51)));
-       BUILD_BUG_ON(HFGITR_EL2_RES0            != (GENMASK_ULL(63, 63) | GENMASK_ULL(61, 61)));
-       BUILD_BUG_ON(HDFGRTR_EL2_RES0           != (GENMASK_ULL(49, 49) | GENMASK_ULL(42, 42) | GENMASK_ULL(39, 38) | GENMASK_ULL(21, 20) | GENMASK_ULL(8, 8)));
-       BUILD_BUG_ON(HDFGWTR_EL2_RES0           != (GENMASK_ULL(63, 63) | GENMASK_ULL(59, 58) | GENMASK_ULL(51, 51) | GENMASK_ULL(47, 47) | GENMASK_ULL(43, 43) | GENMASK_ULL(40, 38) | GENMASK_ULL(34, 34) | GENMASK_ULL(30, 30) | GENMASK_ULL(22, 22) | GENMASK_ULL(9, 9) | GENMASK_ULL(6, 6)));
-       BUILD_BUG_ON(HAFGRTR_EL2_RES0           != (GENMASK_ULL(63, 50) | GENMASK_ULL(16, 5)));
-       BUILD_BUG_ON(HCRX_EL2_RES0              != (GENMASK_ULL(63, 25) | GENMASK_ULL(13, 12)));
-       BUILD_BUG_ON(DACR32_EL2_RES0            != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(PMSCR_EL2_RES0             != (GENMASK_ULL(63, 8) | GENMASK_ULL(2, 2)));
-       BUILD_BUG_ON(TCR2_EL1x_RES0             != (GENMASK_ULL(63, 16) | GENMASK_ULL(13, 12) | GENMASK_ULL(9, 6)));
-       BUILD_BUG_ON(TCR2_EL2_RES0              != (GENMASK_ULL(63, 16)));
-       BUILD_BUG_ON(LORSA_EL1_RES0             != (GENMASK_ULL(63, 52) | GENMASK_ULL(15, 1)));
-       BUILD_BUG_ON(LOREA_EL1_RES0             != (GENMASK_ULL(63, 52) | GENMASK_ULL(15, 0)));
-       BUILD_BUG_ON(LORN_EL1_RES0              != (GENMASK_ULL(63, 8)));
-       BUILD_BUG_ON(LORC_EL1_RES0              != (GENMASK_ULL(63, 10) | GENMASK_ULL(1, 1)));
-       BUILD_BUG_ON(LORID_EL1_RES0             != (GENMASK_ULL(63, 24) | GENMASK_ULL(15, 8)));
-       BUILD_BUG_ON(ISR_EL1_RES0               != (GENMASK_ULL(63, 11) | GENMASK_ULL(5, 0)));
-       BUILD_BUG_ON(ICC_NMIAR1_EL1_RES0        != (GENMASK_ULL(63, 24)));
-       BUILD_BUG_ON(TRBLIMITR_EL1_RES0         != (GENMASK_ULL(11, 7)));
-       BUILD_BUG_ON(TRBBASER_EL1_RES0          != (GENMASK_ULL(11, 0)));
-       BUILD_BUG_ON(TRBSR_EL1_RES0             != (GENMASK_ULL(63, 56) | GENMASK_ULL(25, 24) | GENMASK_ULL(19, 19) | GENMASK_ULL(16, 16)));
-       BUILD_BUG_ON(TRBMAR_EL1_RES0            != (GENMASK_ULL(63, 12)));
-       BUILD_BUG_ON(TRBTRG_EL1_RES0            != (GENMASK_ULL(63, 32)));
-       BUILD_BUG_ON(TRBIDR_EL1_RES0            != (GENMASK_ULL(63, 12) | GENMASK_ULL(7, 6)));
-
-#endif
-}

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 8e60aa4a8dfb06618a789b9d55182a041b5b1e04..c9f4f387155f8cc0097f03a8366105682a81f1a0 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -32,7 +32,6 @@
 
 #include <trace/events/kvm.h>
 
-#include "check-res-bits.h"
 #include "sys_regs.h"
 
 #include "trace.h"
@@ -4110,8 +4109,6 @@ int __init kvm_sys_reg_table_init(void)
        unsigned int i;
        int ret = 0;
 
-       check_res_bits();
-
        /* Make sure tables are unique and in order. */
        valid &= check_sysreg_table(sys_reg_descs, ARRAY_SIZE(sys_reg_descs), false);
        valid &= check_sysreg_table(cp14_regs, ARRAY_SIZE(cp14_regs), true);