[PATCHv3 7/7] x86/tdx: Unaccepted memory support

From: Kirill A. Shutemov
Date: Fri Jan 28 2022 - 15:59:43 EST

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All preparation is complete. Hookup TDX-specific code to accept memory.

There are two tdx_accept_memory() implementations: one in main kernel
and one in the decompressor.

The implementation in core kernel uses tdx_hcall_gpa_intent().
The helper is not available in the decompressor, self-contained
implementation added there instead.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 1 +
arch/x86/boot/compressed/tdx.c | 27 ++++++++++++++++++++
arch/x86/boot/compressed/unaccepted_memory.c | 10 +++++++-
arch/x86/include/asm/shared/tdx.h | 21 +++++++++++++++
arch/x86/include/asm/tdx.h | 19 --------------
arch/x86/kernel/tdx.c | 6 +++++
arch/x86/mm/unaccepted_memory.c | 6 ++++-
7 files changed, 69 insertions(+), 21 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9f4fdd408698..b4ba8cc3e9c0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -886,6 +886,7 @@ config INTEL_TDX_GUEST
select ARCH_HAS_CC_PLATFORM
select X86_MCE
select X86_MEM_ENCRYPT
+ select UNACCEPTED_MEMORY
help
Support running as a guest under Intel TDX. Without this support,
the guest kernel can not boot or run under TDX.
diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c
index f2e1449c74cd..eac80d172e36 100644
--- a/arch/x86/boot/compressed/tdx.c
+++ b/arch/x86/boot/compressed/tdx.c
@@ -6,11 +6,13 @@
#include "../cpuflags.h"
#include "../string.h"
#include "../io.h"
+#include "error.h"

#include <vdso/limits.h>
#include <uapi/asm/vmx.h>

#include <asm/shared/tdx.h>
+#include <asm/page_types.h>

static bool tdx_guest_detected;

@@ -86,3 +88,28 @@ void early_tdx_detect(void)
pio_ops.outw = tdx_outw;
pio_ops.outl = tdx_outl;
}
+
+#define TDACCEPTPAGE 6
+#define TDVMCALL_MAP_GPA 0x10001
+
+void tdx_accept_memory(phys_addr_t start, phys_addr_t end)
+{
+ struct tdx_hypercall_output outl = {0};
+ int i;
+
+ if (__tdx_hypercall(TDX_HYPERCALL_STANDARD, TDVMCALL_MAP_GPA,
+ start, end, 0, 0, &outl)) {
+ error("Cannot accept memory: MapGPA failed\n");
+ }
+
+ /*
+ * For shared->private conversion, accept the page using TDACCEPTPAGE
+ * TDX module call.
+ */
+ for (i = 0; i < (end - start) / PAGE_SIZE; i++) {
+ if (__tdx_module_call(TDACCEPTPAGE, start + i * PAGE_SIZE,
+ 0, 0, 0, NULL)) {
+ error("Cannot accept memory: page accept failed\n");
+ }
+ }
+}
diff --git a/arch/x86/boot/compressed/unaccepted_memory.c b/arch/x86/boot/compressed/unaccepted_memory.c
index d0de7e88dade..a2df2cae5c1b 100644
--- a/arch/x86/boot/compressed/unaccepted_memory.c
+++ b/arch/x86/boot/compressed/unaccepted_memory.c
@@ -1,12 +1,17 @@
// SPDX-License-Identifier: GPL-2.0-only

+#include <asm/shared/tdx.h>
#include "error.h"
#include "misc.h"
+#include "tdx.h"

static inline void __accept_memory(phys_addr_t start, phys_addr_t end)
{
/* Platform-specific memory-acceptance call goes here */
- error("Cannot accept memory");
+ if (early_is_tdx_guest())
+ tdx_accept_memory(start, end);
+ else
+ error("Cannot accept memory");
}

void mark_unaccepted(struct boot_params *params, u64 start, u64 end)
@@ -18,6 +23,9 @@ void mark_unaccepted(struct boot_params *params, u64 start, u64 end)
* *marked* as unaccepted.
*/

+ /* __accept_memory() needs to know if kernel runs in TDX environment */
+ early_tdx_detect();
+
/*
* Accept small regions that might not be able to be represented
* in the bitmap:
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 4a0218bedc75..b17e7d68e0d3 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -3,6 +3,21 @@

#include <linux/types.h>

+/*
+ * Used in __tdx_module_call() to gather the output registers'
+ * values of the TDCALL instruction when requesting services from
+ * the TDX module. This is a software only structure and not part
+ * of the TDX module/VMM ABI
+ */
+struct tdx_module_output {
+ u64 rcx;
+ u64 rdx;
+ u64 r8;
+ u64 r9;
+ u64 r10;
+ u64 r11;
+};
+
/*
* Used in __tdx_hypercall() to gather the output registers' values
* of the TDCALL instruction when requesting services from the VMM.
@@ -23,8 +38,14 @@ struct tdx_hypercall_output {
#define TDX_CPUID_LEAF_ID 0x21
#define TDX_IDENT "IntelTDX "

+/* Used to communicate with the TDX module */
+u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
+ struct tdx_module_output *out);
+
/* Used to request services from the VMM */
u64 __tdx_hypercall(u64 type, u64 fn, u64 r12, u64 r13, u64 r14,
u64 r15, struct tdx_hypercall_output *out);

+extern void tdx_accept_memory(phys_addr_t start, phys_addr_t end);
+
#endif
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index f6a5fb4bf72c..cf0f7f008e6c 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -7,21 +7,6 @@
#include <asm/ptrace.h>
#include <asm/shared/tdx.h>

-/*
- * Used in __tdx_module_call() to gather the output registers'
- * values of the TDCALL instruction when requesting services from
- * the TDX module. This is a software only structure and not part
- * of the TDX module/VMM ABI
- */
-struct tdx_module_output {
- u64 rcx;
- u64 rdx;
- u64 r8;
- u64 r9;
- u64 r10;
- u64 r11;
-};
-
/*
* Used by the #VE exception handler to gather the #VE exception
* info from the TDX module. This is a software only structure
@@ -43,10 +28,6 @@ struct ve_info {
void __init tdx_early_init(void);
bool is_tdx_guest(void);

-/* Used to communicate with the TDX module */
-u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
- struct tdx_module_output *out);
-
bool tdx_get_ve_info(struct ve_info *ve);

bool tdx_handle_virt_exception(struct pt_regs *regs, struct ve_info *ve);
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index 35ef57d778bb..a9bce0a54e1c 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -176,6 +176,12 @@ int tdx_hcall_request_gpa_type(phys_addr_t start, phys_addr_t end, bool enc)
return 0;
}

+void tdx_accept_memory(phys_addr_t start, phys_addr_t end)
+{
+ if (tdx_hcall_request_gpa_type(start, end, true))
+ panic("Accepting memory failed\n");
+}
+
static u64 __cpuidle _tdx_halt(const bool irq_disabled, const bool do_sti)
{
/*
diff --git a/arch/x86/mm/unaccepted_memory.c b/arch/x86/mm/unaccepted_memory.c
index adcac22dfe75..2c4ef49a0c9b 100644
--- a/arch/x86/mm/unaccepted_memory.c
+++ b/arch/x86/mm/unaccepted_memory.c
@@ -5,6 +5,7 @@

#include <asm/io.h>
#include <asm/setup.h>
+#include <asm/shared/tdx.h>
#include <asm/unaccepted_memory.h>

static DEFINE_SPINLOCK(unaccepted_memory_lock);
@@ -22,7 +23,10 @@ static void __accept_memory(phys_addr_t start, phys_addr_t end)
for_each_set_bitrange_from(rs, re, unaccepted_memory,
DIV_ROUND_UP(end, PMD_SIZE)) {
/* Platform-specific memory-acceptance call goes here */
- panic("Cannot accept memory");
+ if (cc_platform_has(CC_ATTR_GUEST_TDX))
+ tdx_accept_memory(rs * PMD_SIZE, re * PMD_SIZE);
+ else
+ panic("Cannot accept memory");
bitmap_clear(unaccepted_memory, rs, re - rs);
}
}
--
2.34.1

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