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authorLinus Torvalds <torvalds@linux-foundation.org>2023-02-25 20:11:30 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2023-02-25 20:11:30 +0300
commitd8e473182ab9e85708067be81d20424045d939fa (patch)
tree53336e3105f7054b46fb9fd75fdbe3dbb3aa79de /arch
parent489fa31ea873282b41046d412ec741f93946fc2d (diff)
parent1e70c680375aa33cca97bff0bca68c0f82f5023c (diff)
downloadlinux-d8e473182ab9e85708067be81d20424045d939fa.tar.xz
Merge tag 'x86_tdx_for_6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull Intel Trust Domain Extensions (TDX) updates from Dave Hansen: "Other than a minor fixup, the content here is to ensure that TDX guests never see virtualization exceptions (#VE's) that might be induced by the untrusted VMM. This is a highly desirable property. Without it, #VE exception handling would fall somewhere between NMIs, machine checks and total insanity. With it, #VE handling remains pretty mundane. Summary: - Fixup comment typo - Prevent unexpected #VE's from: - Hosts removing perfectly good guest mappings (SEPT_VE_DISABLE) - Excessive #VE notifications (NOTIFY_ENABLES) which are delivered via a #VE" * tag 'x86_tdx_for_6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/tdx: Do not corrupt frame-pointer in __tdx_hypercall() x86/tdx: Disable NOTIFY_ENABLES x86/tdx: Relax SEPT_VE_DISABLE check for debug TD x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE x86/tdx: Expand __tdx_hypercall() to handle more arguments x86/tdx: Refactor __tdx_hypercall() to allow pass down more arguments x86/tdx: Add more registers to struct tdx_hypercall_args x86/tdx: Fix typo in comment in __tdx_hypercall()
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/coco/tdx/tdcall.S81
-rw-r--r--arch/x86/coco/tdx/tdx.c62
-rw-r--r--arch/x86/include/asm/shared/tdx.h6
-rw-r--r--arch/x86/kernel/asm-offsets.c6
4 files changed, 130 insertions, 25 deletions
diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S
index ad0d51f03cb4..6a255e6809bc 100644
--- a/arch/x86/coco/tdx/tdcall.S
+++ b/arch/x86/coco/tdx/tdcall.S
@@ -13,6 +13,12 @@
/*
* Bitmasks of exposed registers (with VMM).
*/
+#define TDX_RDX BIT(2)
+#define TDX_RBX BIT(3)
+#define TDX_RSI BIT(6)
+#define TDX_RDI BIT(7)
+#define TDX_R8 BIT(8)
+#define TDX_R9 BIT(9)
#define TDX_R10 BIT(10)
#define TDX_R11 BIT(11)
#define TDX_R12 BIT(12)
@@ -27,9 +33,9 @@
* details can be found in TDX GHCI specification, section
* titled "TDCALL [TDG.VP.VMCALL] leaf".
*/
-#define TDVMCALL_EXPOSE_REGS_MASK ( TDX_R10 | TDX_R11 | \
- TDX_R12 | TDX_R13 | \
- TDX_R14 | TDX_R15 )
+#define TDVMCALL_EXPOSE_REGS_MASK \
+ ( TDX_RDX | TDX_RBX | TDX_RSI | TDX_RDI | TDX_R8 | TDX_R9 | \
+ TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15 )
.section .noinstr.text, "ax"
@@ -126,25 +132,38 @@ SYM_FUNC_START(__tdx_hypercall)
push %r14
push %r13
push %r12
+ push %rbx
+
+ /* Free RDI and RSI to be used as TDVMCALL arguments */
+ movq %rdi, %rax
+ push %rsi
+
+ /* Copy hypercall registers from arg struct: */
+ movq TDX_HYPERCALL_r8(%rax), %r8
+ movq TDX_HYPERCALL_r9(%rax), %r9
+ movq TDX_HYPERCALL_r10(%rax), %r10
+ movq TDX_HYPERCALL_r11(%rax), %r11
+ movq TDX_HYPERCALL_r12(%rax), %r12
+ movq TDX_HYPERCALL_r13(%rax), %r13
+ movq TDX_HYPERCALL_r14(%rax), %r14
+ movq TDX_HYPERCALL_r15(%rax), %r15
+ movq TDX_HYPERCALL_rdi(%rax), %rdi
+ movq TDX_HYPERCALL_rsi(%rax), %rsi
+ movq TDX_HYPERCALL_rbx(%rax), %rbx
+ movq TDX_HYPERCALL_rdx(%rax), %rdx
+
+ push %rax
/* Mangle function call ABI into TDCALL ABI: */
/* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */
xor %eax, %eax
- /* Copy hypercall registers from arg struct: */
- movq TDX_HYPERCALL_r10(%rdi), %r10
- movq TDX_HYPERCALL_r11(%rdi), %r11
- movq TDX_HYPERCALL_r12(%rdi), %r12
- movq TDX_HYPERCALL_r13(%rdi), %r13
- movq TDX_HYPERCALL_r14(%rdi), %r14
- movq TDX_HYPERCALL_r15(%rdi), %r15
-
movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx
tdcall
/*
- * RAX==0 indicates a failure of the TDVMCALL mechanism itself and that
+ * RAX!=0 indicates a failure of the TDVMCALL mechanism itself and that
* something has gone horribly wrong with the TDX module.
*
* The return status of the hypercall operation is in a separate
@@ -154,30 +173,46 @@ SYM_FUNC_START(__tdx_hypercall)
testq %rax, %rax
jne .Lpanic
- /* TDVMCALL leaf return code is in R10 */
- movq %r10, %rax
+ pop %rax
/* Copy hypercall result registers to arg struct if needed */
- testq $TDX_HCALL_HAS_OUTPUT, %rsi
+ testq $TDX_HCALL_HAS_OUTPUT, (%rsp)
jz .Lout
- movq %r10, TDX_HYPERCALL_r10(%rdi)
- movq %r11, TDX_HYPERCALL_r11(%rdi)
- movq %r12, TDX_HYPERCALL_r12(%rdi)
- movq %r13, TDX_HYPERCALL_r13(%rdi)
- movq %r14, TDX_HYPERCALL_r14(%rdi)
- movq %r15, TDX_HYPERCALL_r15(%rdi)
+ movq %r8, TDX_HYPERCALL_r8(%rax)
+ movq %r9, TDX_HYPERCALL_r9(%rax)
+ movq %r10, TDX_HYPERCALL_r10(%rax)
+ movq %r11, TDX_HYPERCALL_r11(%rax)
+ movq %r12, TDX_HYPERCALL_r12(%rax)
+ movq %r13, TDX_HYPERCALL_r13(%rax)
+ movq %r14, TDX_HYPERCALL_r14(%rax)
+ movq %r15, TDX_HYPERCALL_r15(%rax)
+ movq %rdi, TDX_HYPERCALL_rdi(%rax)
+ movq %rsi, TDX_HYPERCALL_rsi(%rax)
+ movq %rbx, TDX_HYPERCALL_rbx(%rax)
+ movq %rdx, TDX_HYPERCALL_rdx(%rax)
.Lout:
+ /* TDVMCALL leaf return code is in R10 */
+ movq %r10, %rax
+
/*
* Zero out registers exposed to the VMM to avoid speculative execution
* with VMM-controlled values. This needs to include all registers
- * present in TDVMCALL_EXPOSE_REGS_MASK (except R12-R15). R12-R15
- * context will be restored.
+ * present in TDVMCALL_EXPOSE_REGS_MASK, except RBX, and R12-R15 which
+ * will be restored.
*/
+ xor %r8d, %r8d
+ xor %r9d, %r9d
xor %r10d, %r10d
xor %r11d, %r11d
+ xor %rdi, %rdi
+ xor %rdx, %rdx
+
+ /* Remove TDX_HCALL_* flags from the stack */
+ pop %rsi
/* Restore callee-saved GPRs as mandated by the x86_64 ABI */
+ pop %rbx
pop %r12
pop %r13
pop %r14
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 3bd111d5e6a0..055300e08fb3 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -19,9 +19,14 @@
#define TDX_GET_VEINFO 3
#define TDX_GET_REPORT 4
#define TDX_ACCEPT_PAGE 6
+#define TDX_WR 8
+
+/* TDCS fields. To be used by TDG.VM.WR and TDG.VM.RD module calls */
+#define TDCS_NOTIFY_ENABLES 0x9100000000000010
/* TDX hypercall Leaf IDs */
#define TDVMCALL_MAP_GPA 0x10001
+#define TDVMCALL_REPORT_FATAL_ERROR 0x10003
/* MMIO direction */
#define EPT_READ 0
@@ -37,6 +42,7 @@
#define VE_GET_PORT_NUM(e) ((e) >> 16)
#define VE_IS_IO_STRING(e) ((e) & BIT(4))
+#define ATTR_DEBUG BIT(0)
#define ATTR_SEPT_VE_DISABLE BIT(28)
/* TDX Module call error codes */
@@ -141,6 +147,41 @@ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport)
}
EXPORT_SYMBOL_GPL(tdx_mcall_get_report0);
+static void __noreturn tdx_panic(const char *msg)
+{
+ struct tdx_hypercall_args args = {
+ .r10 = TDX_HYPERCALL_STANDARD,
+ .r11 = TDVMCALL_REPORT_FATAL_ERROR,
+ .r12 = 0, /* Error code: 0 is Panic */
+ };
+ union {
+ /* Define register order according to the GHCI */
+ struct { u64 r14, r15, rbx, rdi, rsi, r8, r9, rdx; };
+
+ char str[64];
+ } message;
+
+ /* VMM assumes '\0' in byte 65, if the message took all 64 bytes */
+ strncpy(message.str, msg, 64);
+
+ args.r8 = message.r8;
+ args.r9 = message.r9;
+ args.r14 = message.r14;
+ args.r15 = message.r15;
+ args.rdi = message.rdi;
+ args.rsi = message.rsi;
+ args.rbx = message.rbx;
+ args.rdx = message.rdx;
+
+ /*
+ * This hypercall should never return and it is not safe
+ * to keep the guest running. Call it forever if it
+ * happens to return.
+ */
+ while (1)
+ __tdx_hypercall(&args, 0);
+}
+
static void tdx_parse_tdinfo(u64 *cc_mask)
{
struct tdx_module_output out;
@@ -172,8 +213,15 @@ static void tdx_parse_tdinfo(u64 *cc_mask)
* TD-private memory. Only VMM-shared memory (MMIO) will #VE.
*/
td_attr = out.rdx;
- if (!(td_attr & ATTR_SEPT_VE_DISABLE))
- panic("TD misconfiguration: SEPT_VE_DISABLE attibute must be set.\n");
+ if (!(td_attr & ATTR_SEPT_VE_DISABLE)) {
+ const char *msg = "TD misconfiguration: SEPT_VE_DISABLE attribute must be set.";
+
+ /* Relax SEPT_VE_DISABLE check for debug TD. */
+ if (td_attr & ATTR_DEBUG)
+ pr_warn("%s\n", msg);
+ else
+ tdx_panic(msg);
+ }
}
/*
@@ -617,6 +665,11 @@ static int virt_exception_user(struct pt_regs *regs, struct ve_info *ve)
}
}
+static inline bool is_private_gpa(u64 gpa)
+{
+ return gpa == cc_mkenc(gpa);
+}
+
/*
* Handle the kernel #VE.
*
@@ -635,6 +688,8 @@ static int virt_exception_kernel(struct pt_regs *regs, struct ve_info *ve)
case EXIT_REASON_CPUID:
return handle_cpuid(regs, ve);
case EXIT_REASON_EPT_VIOLATION:
+ if (is_private_gpa(ve->gpa))
+ panic("Unexpected EPT-violation on private memory.");
return handle_mmio(regs, ve);
case EXIT_REASON_IO_INSTRUCTION:
return handle_io(regs, ve);
@@ -801,6 +856,9 @@ void __init tdx_early_init(void)
tdx_parse_tdinfo(&cc_mask);
cc_set_mask(cc_mask);
+ /* Kernel does not use NOTIFY_ENABLES and does not need random #VEs */
+ tdx_module_call(TDX_WR, 0, TDCS_NOTIFY_ENABLES, 0, -1ULL, NULL);
+
/*
* All bits above GPA width are reserved and kernel treats shared bit
* as flag, not as part of physical address.
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 559176887791..4a03993e0785 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -21,12 +21,18 @@
* This is a software only structure and not part of the TDX module/VMM ABI.
*/
struct tdx_hypercall_args {
+ u64 r8;
+ u64 r9;
u64 r10;
u64 r11;
u64 r12;
u64 r13;
u64 r14;
u64 r15;
+ u64 rdi;
+ u64 rsi;
+ u64 rbx;
+ u64 rdx;
};
/* Used to request services from the VMM */
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index ef9e951415c5..283dcd2f62c8 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -76,12 +76,18 @@ static void __used common(void)
OFFSET(TDX_MODULE_r11, tdx_module_output, r11);
BLANK();
+ OFFSET(TDX_HYPERCALL_r8, tdx_hypercall_args, r8);
+ OFFSET(TDX_HYPERCALL_r9, tdx_hypercall_args, r9);
OFFSET(TDX_HYPERCALL_r10, tdx_hypercall_args, r10);
OFFSET(TDX_HYPERCALL_r11, tdx_hypercall_args, r11);
OFFSET(TDX_HYPERCALL_r12, tdx_hypercall_args, r12);
OFFSET(TDX_HYPERCALL_r13, tdx_hypercall_args, r13);
OFFSET(TDX_HYPERCALL_r14, tdx_hypercall_args, r14);
OFFSET(TDX_HYPERCALL_r15, tdx_hypercall_args, r15);
+ OFFSET(TDX_HYPERCALL_rdi, tdx_hypercall_args, rdi);
+ OFFSET(TDX_HYPERCALL_rsi, tdx_hypercall_args, rsi);
+ OFFSET(TDX_HYPERCALL_rbx, tdx_hypercall_args, rbx);
+ OFFSET(TDX_HYPERCALL_rdx, tdx_hypercall_args, rdx);
BLANK();
OFFSET(BP_scratch, boot_params, scratch);