Messages in this thread Patch in this message | | | From | Kuppuswamy Sathyanarayanan <> | Subject | [PATCH v2 05/10] x86/tdx: Handle port I/O | Date | Sat, 26 Jun 2021 07:17:13 -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> Reviewed-by: Dan Williams <dan.j.williams@intel.com> ---
Changes since v1: * Fixed comments for tdg_handle_io(). * Used _tdx_hypercall() instead of __tdx_hypercall() in tdg_handle_io().
arch/x86/include/asm/io.h | 7 +++++-- arch/x86/kernel/tdx.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 50f9eb17d364..b677f81168a0 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -40,6 +40,7 @@ #include <linux/string.h> #include <linux/compiler.h> +#include <linux/protected_guest.h> #include <asm/page.h> #include <asm/early_ioremap.h> #include <asm/pgtable_types.h> @@ -309,7 +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() || \ + prot_guest_has(PR_GUEST_UNROLL_STRING_IO)) { \ unsigned type *value = (unsigned type *)addr; \ while (count) { \ out##bwl(*value, port); \ @@ -325,7 +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() || \ + prot_guest_has(PR_GUEST_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 a20bdbdc2bc8..ad035a5230e9 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -177,6 +177,34 @@ static void tdg_handle_cpuid(struct pt_regs *regs) regs->dx = out.r15; } +/* + * tdx_handle_early_io() cannot be re-used in #VE handler for handling + * I/O because the way of handling string I/O is different between + * normal and early I/O case. Also, once trace support is enabled, + * tdg_handle_io() will be extended to use trace calls which is also + * not valid for early I/O cases. + */ +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; @@ -223,6 +251,9 @@ 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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