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arm64: Get rid of CONFIG_ARM64_VHE

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CONFIG_ARM64_VHE was introduced with ARMv8.1 (some 7 years ago),
and has been enabled by default for almost all that time.

Given that newer systems that are VHE capable are finally becoming
available, and that some systems are even incapable of not running VHE,
drop the configuration altogether.

Anyone willing to stick to non-VHE on VHE hardware for obscure
reasons should use the 'kvm-arm.mode=nvhe' command-line option.

Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210408131010.1109027-4-maz@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2021-04-08 14:10:10 +01:00 committed by Catalin Marinas
parent 31a32b49b8
commit 2d726d0db6
4 changed files with 1 additions and 28 deletions
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3
Documentation/admin-guide/kernel-parameters.txt
View File

@ -2279,8 +2279,7 @@
state is kept private from the host.
Not valid if the kernel is running in EL2.
Defaults to VHE/nVHE based on hardware support and
the value of CONFIG_ARM64_VHE.
Defaults to VHE/nVHE based on hardware support.
kvm-arm.vgic_v3_group0_trap=
[KVM,ARM] Trap guest accesses to GICv3 group-0

20
arch/arm64/Kconfig
View File

@ -1416,19 +1416,6 @@ config ARM64_USE_LSE_ATOMICS
built with binutils >= 2.25 in order for the new instructions
to be used.
config ARM64_VHE
bool "Enable support for Virtualization Host Extensions (VHE)"
default y
help
Virtualization Host Extensions (VHE) allow the kernel to run
directly at EL2 (instead of EL1) on processors that support
it. This leads to better performance for KVM, as they reduce
the cost of the world switch.
Selecting this option allows the VHE feature to be detected
at runtime, and does not affect processors that do not
implement this feature.
endmenu
menu "ARMv8.2 architectural features"
@ -1684,7 +1671,6 @@ endmenu
config ARM64_SVE
bool "ARM Scalable Vector Extension support"
default y
depends on !KVM || ARM64_VHE
help
The Scalable Vector Extension (SVE) is an extension to the AArch64
execution state which complements and extends the SIMD functionality
@ -1713,12 +1699,6 @@ config ARM64_SVE
booting the kernel. If unsure and you are not observing these
symptoms, you should assume that it is safe to say Y.
CPUs that support SVE are architecturally required to support the
Virtualization Host Extensions (VHE), so the kernel makes no
provision for supporting SVE alongside KVM without VHE enabled.
Thus, you will need to enable CONFIG_ARM64_VHE if you want to support
KVM in the same kernel image.
config ARM64_MODULE_PLTS
bool "Use PLTs to allow module memory to spill over into vmalloc area"
depends on MODULES

4
arch/arm64/kernel/cpufeature.c
View File

@ -1623,7 +1623,6 @@ int get_cpu_with_amu_feat(void)
}
#endif
#ifdef CONFIG_ARM64_VHE
static bool runs_at_el2(const struct arm64_cpu_capabilities *entry, int __unused)
{
return is_kernel_in_hyp_mode();
@ -1642,7 +1641,6 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
if (!alternative_is_applied(ARM64_HAS_VIRT_HOST_EXTN))
write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
}
#endif
static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused)
{
@ -1845,7 +1843,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
.matches = has_no_hw_prefetch,
},
#ifdef CONFIG_ARM64_VHE
{
.desc = "Virtualization Host Extensions",
.capability = ARM64_HAS_VIRT_HOST_EXTN,
@ -1853,7 +1850,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = runs_at_el2,
.cpu_enable = cpu_copy_el2regs,
},
#endif /* CONFIG_ARM64_VHE */
{
.desc = "32-bit EL0 Support",
.capability = ARM64_HAS_32BIT_EL0,

2
arch/arm64/kernel/hyp-stub.S
View File

@ -224,7 +224,6 @@ SYM_FUNC_END(__hyp_reset_vectors)
* Entry point to switch to VHE if deemed capable
*/
SYM_FUNC_START(switch_to_vhe)
#ifdef CONFIG_ARM64_VHE
// Need to have booted at EL2
adr_l x1, __boot_cpu_mode
ldr w0, [x1]
@ -240,6 +239,5 @@ SYM_FUNC_START(switch_to_vhe)
mov x0, #HVC_VHE_RESTART
hvc #0
1:
#endif
ret
SYM_FUNC_END(switch_to_vhe)