Messages in this thread Patch in this message | | | From | Kuppuswamy Sathyanarayanan <> | Subject | [RFC v2-fix-v2 3/3] x86/tdx: Handle port I/O | Date | Tue, 8 Jun 2021 08:40:23 -0700 |
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From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
TDX hypervisors cannot emulate instructions directly. This includes port IO which is normally emulated in the hypervisor. All port IO instructions inside TDX trigger the #VE exception in the guest and would be normally emulated there.
Also string I/O is not supported in TDX guest. So, unroll the string I/O operation into a loop operating on one element at a time. This method is similar to AMD SEV, so just extend the support for TDX guest platform.
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> --- Changes since RFC v2-fix-v1: * Fixed commit log to adapt to decompression support code split.
arch/x86/include/asm/io.h | 6 ++++-- arch/x86/kernel/tdx.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 391205dace98..e01d8bf2b37a 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -310,7 +310,8 @@ static inline unsigned type in##bwl##_p(int port) \ \ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ { \ - if (sev_key_active()) { \ + if (sev_key_active() || \ + protected_guest_has(VM_UNROLL_STRING_IO)) { \ unsigned type *value = (unsigned type *)addr; \ while (count) { \ out##bwl(*value, port); \ @@ -326,7 +327,8 @@ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ \ static inline void ins##bwl(int port, void *addr, unsigned long count) \ { \ - if (sev_key_active()) { \ + if (sev_key_active() || \ + protected_guest_has(VM_UNROLL_STRING_IO)) { \ unsigned type *value = (unsigned type *)addr; \ while (count) { \ *value = in##bwl(port); \ diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c index 3410cfc8a988..48a0cc2663ea 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -201,6 +201,31 @@ static void tdg_handle_cpuid(struct pt_regs *regs) regs->dx = out.r15; } +/* + * Since the way we fail for string case is different we cannot + * reuse tdx_handle_early_io(). + */ +static void tdg_handle_io(struct pt_regs *regs, u32 exit_qual) +{ + struct tdx_hypercall_output outh; + int out = VE_IS_IO_OUT(exit_qual); + int size = VE_GET_IO_SIZE(exit_qual); + int port = VE_GET_PORT_NUM(exit_qual); + u64 mask = GENMASK(8 * size, 0); + bool string = VE_IS_IO_STRING(exit_qual); + int ret; + + /* I/O strings ops are unrolled at build time. */ + BUG_ON(string); + + ret = __tdx_hypercall(EXIT_REASON_IO_INSTRUCTION, size, out, port, + regs->ax, &outh); + if (!out) { + regs->ax &= ~mask; + regs->ax |= (ret ? UINT_MAX : outh.r11) & mask; + } +} + unsigned long tdg_get_ve_info(struct ve_info *ve) { u64 ret; @@ -247,6 +272,9 @@ int tdg_handle_virtualization_exception(struct pt_regs *regs, case EXIT_REASON_CPUID: tdg_handle_cpuid(regs); break; + case EXIT_REASON_IO_INSTRUCTION: + tdg_handle_io(regs, ve->exit_qual); + break; default: pr_warn("Unexpected #VE: %lld\n", ve->exit_reason); return -EFAULT; -- 2.25.1
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