From: "Kirill A. Shutemov" <[email protected]>
Per Guest-Host-Communication Interface (GHCI) for Intel Trust Domain Extensions (Intel TDX) specification, sec 3.8, TDVMCALL[Instruction.HLT] provides HLT operation. Use it to implement halt() and safe_halt() paravirtualization calls. The same TDVMCALL is used to handle #VE exception due to EXIT_REASON_HLT. Signed-off-by: Kirill A. Shutemov <[email protected]> Reviewed-by: Andi Kleen <[email protected]> Signed-off-by: Kuppuswamy Sathyanarayanan <[email protected]> --- arch/x86/include/asm/tdx.h | 5 ++++ arch/x86/kernel/tdx.c | 61 ++++++++++++++++++++++++++++++++++---- 2 files changed, 60 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h index 90eb61b07d1f..b98de067257b 100644 --- a/arch/x86/include/asm/tdx.h +++ b/arch/x86/include/asm/tdx.h @@ -14,9 +14,14 @@ */ #define TDCALL ".byte 0x66,0x0f,0x01,0xcc" +#define TDVMCALL 0 #define TDINFO 1 #define TDGETVEINFO 3 +/* TDVMCALL R10 Input */ +#define TDVMCALL_STANDARD 0 +#define TDVMCALL_VENDOR 1 + /* Common API to check TDX support in decompression and common kernel code. */ bool is_tdx_guest(void); diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c index ae2d5c847700..25dd33bc2e49 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -51,6 +51,45 @@ static void tdx_get_info(void) td_info.attributes = rdx; } +static __cpuidle void tdx_halt(void) +{ + register long r10 asm("r10") = TDVMCALL_STANDARD; + register long r11 asm("r11") = EXIT_REASON_HLT; + register long rcx asm("rcx"); + long ret; + + /* Allow to pass R10 and R11 down to the VMM */ + rcx = BIT(10) | BIT(11); + + asm volatile(TDCALL + : "=a"(ret), "=r"(r10), "=r"(r11) + : "a"(TDVMCALL), "r"(rcx), "r"(r10), "r"(r11) + : ); + + /* It should never fail */ + BUG_ON(ret || r10); +} + +static __cpuidle void tdx_safe_halt(void) +{ + register long r10 asm("r10") = TDVMCALL_STANDARD; + register long r11 asm("r11") = EXIT_REASON_HLT; + register long rcx asm("rcx"); + long ret; + + /* Allow to pass R10 and R11 down to the VMM */ + rcx = BIT(10) | BIT(11); + + /* Enable interrupts next to the TDVMCALL to avoid performance degradation */ + asm volatile("sti\n\t" TDCALL + : "=a"(ret), "=r"(r10), "=r"(r11) + : "a"(TDVMCALL), "r"(rcx), "r"(r10), "r"(r11) + : ); + + /* It should never fail */ + BUG_ON(ret || r10); +} + void __init tdx_early_init(void) { if (!cpuid_has_tdx_guest()) @@ -60,6 +99,9 @@ void __init tdx_early_init(void) tdx_get_info(); + pv_ops.irq.safe_halt = tdx_safe_halt; + pv_ops.irq.halt = tdx_halt; + pr_info("TDX guest is initialized\n"); } @@ -86,10 +128,17 @@ unsigned long tdx_get_ve_info(struct ve_info *ve) int tdx_handle_virtualization_exception(struct pt_regs *regs, struct ve_info *ve) { - /* - * TODO: Add handler support for various #VE exit - * reasons - */ - pr_warn("Unexpected #VE: %d\n", ve->exit_reason); - return -EFAULT; + switch (ve->exit_reason) { + case EXIT_REASON_HLT: + tdx_halt(); + break; + default: + pr_warn("Unexpected #VE: %d\n", ve->exit_reason); + return -EFAULT; + } + + /* After successful #VE handling, move the IP */ + regs->ip += ve->instr_len; + + return ret; } -- 2.25.1
