diff options
| -rw-r--r-- | arch/arm64/Kconfig | 13 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 28 |
2 files changed, 40 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 8cc6228..cf118d9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -750,6 +750,19 @@ config ARM64_LSE_ATOMICS not support these instructions and requires the kernel to be built with binutils >= 2.25. +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 endmenu diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 917d981..6f2f377 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -30,6 +30,7 @@ #include <asm/cache.h> #include <asm/cputype.h> #include <asm/kernel-pgtable.h> +#include <asm/kvm_arm.h> #include <asm/memory.h> #include <asm/pgtable-hwdef.h> #include <asm/pgtable.h> @@ -464,9 +465,27 @@ CPU_LE( bic x0, x0, #(3 << 24) ) // Clear the EE and E0E bits for EL1 isb ret +2: +#ifdef CONFIG_ARM64_VHE + /* + * Check for VHE being present. For the rest of the EL2 setup, + * x2 being non-zero indicates that we do have VHE, and that the + * kernel is intended to run at EL2. + */ + mrs x2, id_aa64mmfr1_el1 + ubfx x2, x2, #8, #4 +#else + mov x2, xzr +#endif + /* Hyp configuration. */ -2: mov x0, #(1 << 31) // 64-bit EL1 + mov x0, #HCR_RW // 64-bit EL1 + cbz x2, set_hcr + orr x0, x0, #HCR_TGE // Enable Host Extensions + orr x0, x0, #HCR_E2H +set_hcr: msr hcr_el2, x0 + isb /* Generic timers. */ mrs x0, cnthctl_el2 @@ -526,6 +545,13 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems /* Stage-2 translation */ msr vttbr_el2, xzr + cbz x2, install_el2_stub + + mov w20, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2 + isb + ret + +install_el2_stub: /* Hypervisor stub */ adrp x0, __hyp_stub_vectors add x0, x0, #:lo12:__hyp_stub_vectors |