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Message-Id: <20210804191855.2901927-6-sathyanarayanan.kuppuswamy@linux.intel.com>
Date: Wed, 4 Aug 2021 12:18:50 -0700
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...nel.org>
Cc: Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
Tony Luck <tony.luck@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Andi Kleen <ak@...ux.intel.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Sean Christopherson <seanjc@...gle.com>,
Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 05/10] x86/tdx: Handle port I/O
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.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.
Add a new protected guest flag PATTR_GUEST_UNROLL_STRING_IO
to add string unroll support in asm/io.h
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
---
Changes since v3:
* Included PATTR_GUEST_UNROLL_STRING_IO protected guest flag
addition change in this patch.
* Rebased on top of Tom Lendacks protected guest change.
Changes since v2:
* None
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 | 32 ++++++++++++++++++++++++++++++++
include/linux/protected_guest.h | 1 +
3 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 50f9eb17d364..4c9e06a81ebe 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(PATTR_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(PATTR_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 b9a66f8de5e5..c6dd7960fd2b 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -62,6 +62,7 @@ bool tdx_prot_guest_has(unsigned long flag)
{
switch (flag) {
case PATTR_GUEST_TDX:
+ case PATTR_GUEST_UNROLL_STRING_IO:
return cpu_feature_enabled(X86_FEATURE_TDX_GUEST);
}
@@ -173,6 +174,34 @@ 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;
@@ -219,6 +248,9 @@ 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;
diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
index 9085f5dd834c..1a350c3fcfe2 100644
--- a/include/linux/protected_guest.h
+++ b/include/linux/protected_guest.h
@@ -16,6 +16,7 @@
#define PATTR_HOST_MEM_ENCRYPT 1 /* Host encrypted memory */
#define PATTR_GUEST_MEM_ENCRYPT 2 /* Guest encrypted memory */
#define PATTR_GUEST_PROT_STATE 3 /* Guest encrypted state */
+#define PATTR_GUEST_UNROLL_STRING_IO 4 /* Unrolled string IO */
/* 0x800 - 0x8ff reserved for AMD */
#define PATTR_SME 0x800
--
2.25.1
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