Merge tag 'sev_fixes_for_v6.6' of //git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Borislav Petkov:
 "Take care of a race between when the #VC exception is raised and when
  the guest kernel gets to emulate certain instructions in SEV-{ES,SNP}
  guests by:

   - disabling emulation of MMIO instructions when coming from user mode

   - checking the IO permission bitmap before emulating IO instructions
     and verifying the memory operands of INS/OUTS insns"

* tag 'sev_fixes_for_v6.6' of //git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sev: Check for user-space IOIO pointing to kernel space
  x86/sev: Check IOBM for IOIO exceptions from user-space
  x86/sev: Disable MMIO emulation from user mode

3 files changed, 84 insertions, 9 deletions

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index dc8c876fbd8f..80d76aea1f7b 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -103,6 +103,16 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
 	return ES_OK;
 }
 
+static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t size)
+{
+	return ES_OK;
+}
+
+static bool fault_in_kernel_space(unsigned long address)
+{
+	return false;
+}
+
 #undef __init
 #define __init
 
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index dcf325b7b022..ccb0915e84e1 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -632,6 +632,23 @@ fail:
 	sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
 }
 
+static enum es_result vc_insn_string_check(struct es_em_ctxt *ctxt,
+					   unsigned long address,
+					   bool write)
+{
+	if (user_mode(ctxt->regs) && fault_in_kernel_space(address)) {
+		ctxt->fi.vector     = X86_TRAP_PF;
+		ctxt->fi.error_code = X86_PF_USER;
+		ctxt->fi.cr2        = address;
+		if (write)
+			ctxt->fi.error_code |= X86_PF_WRITE;
+
+		return ES_EXCEPTION;
+	}
+
+	return ES_OK;
+}
+
 static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
 					  void *src, char *buf,
 					  unsigned int data_size,
@@ -639,7 +656,12 @@ static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
 					  bool backwards)
 {
 	int i, b = backwards ? -1 : 1;
-	enum es_result ret = ES_OK;
+	unsigned long address = (unsigned long)src;
+	enum es_result ret;
+
+	ret = vc_insn_string_check(ctxt, address, false);
+	if (ret != ES_OK)
+		return ret;
 
 	for (i = 0; i < count; i++) {
 		void *s = src + (i * data_size * b);
@@ -660,7 +682,12 @@ static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
 					   bool backwards)
 {
 	int i, s = backwards ? -1 : 1;
-	enum es_result ret = ES_OK;
+	unsigned long address = (unsigned long)dst;
+	enum es_result ret;
+
+	ret = vc_insn_string_check(ctxt, address, true);
+	if (ret != ES_OK)
+		return ret;
 
 	for (i = 0; i < count; i++) {
 		void *d = dst + (i * data_size * s);
@@ -696,6 +723,9 @@ static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
 static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
 {
 	struct insn *insn = &ctxt->insn;
+	size_t size;
+	u64 port;
+
 	*exitinfo = 0;
 
 	switch (insn->opcode.bytes[0]) {
@@ -704,7 +734,7 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
 	case 0x6d:
 		*exitinfo |= IOIO_TYPE_INS;
 		*exitinfo |= IOIO_SEG_ES;
-		*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+		port	   = ctxt->regs->dx & 0xffff;
 		break;
 
 	/* OUTS opcodes */
@@ -712,41 +742,43 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
 	case 0x6f:
 		*exitinfo |= IOIO_TYPE_OUTS;
 		*exitinfo |= IOIO_SEG_DS;
-		*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+		port	   = ctxt->regs->dx & 0xffff;
 		break;
 
 	/* IN immediate opcodes */
 	case 0xe4:
 	case 0xe5:
 		*exitinfo |= IOIO_TYPE_IN;
-		*exitinfo |= (u8)insn->immediate.value << 16;
+		port	   = (u8)insn->immediate.value & 0xffff;
 		break;
 
 	/* OUT immediate opcodes */
 	case 0xe6:
 	case 0xe7:
 		*exitinfo |= IOIO_TYPE_OUT;
-		*exitinfo |= (u8)insn->immediate.value << 16;
+		port	   = (u8)insn->immediate.value & 0xffff;
 		break;
 
 	/* IN register opcodes */
 	case 0xec:
 	case 0xed:
 		*exitinfo |= IOIO_TYPE_IN;
-		*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+		port	   = ctxt->regs->dx & 0xffff;
 		break;
 
 	/* OUT register opcodes */
 	case 0xee:
 	case 0xef:
 		*exitinfo |= IOIO_TYPE_OUT;
-		*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
+		port	   = ctxt->regs->dx & 0xffff;
 		break;
 
 	default:
 		return ES_DECODE_FAILED;
 	}
 
+	*exitinfo |= port << 16;
+
 	switch (insn->opcode.bytes[0]) {
 	case 0x6c:
 	case 0x6e:
@@ -756,12 +788,15 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
 	case 0xee:
 		/* Single byte opcodes */
 		*exitinfo |= IOIO_DATA_8;
+		size       = 1;
 		break;
 	default:
 		/* Length determined by instruction parsing */
 		*exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
 						     : IOIO_DATA_32;
+		size       = (insn->opnd_bytes == 2) ? 2 : 4;
 	}
+
 	switch (insn->addr_bytes) {
 	case 2:
 		*exitinfo |= IOIO_ADDR_16;
@@ -777,7 +812,7 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
 	if (insn_has_rep_prefix(insn))
 		*exitinfo |= IOIO_REP;
 
-	return ES_OK;
+	return vc_ioio_check(ctxt, (u16)port, size);
 }
 
 static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index d8c1e3be74c0..6395bfd87b68 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -524,6 +524,33 @@ static enum es_result vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt
 	return ES_OK;
 }
 
+static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t size)
+{
+	BUG_ON(size > 4);
+
+	if (user_mode(ctxt->regs)) {
+		struct thread_struct *t = &current->thread;
+		struct io_bitmap *iobm = t->io_bitmap;
+		size_t idx;
+
+		if (!iobm)
+			goto fault;
+
+		for (idx = port; idx < port + size; ++idx) {
+			if (test_bit(idx, iobm->bitmap))
+				goto fault;
+		}
+	}
+
+	return ES_OK;
+
+fault:
+	ctxt->fi.vector = X86_TRAP_GP;
+	ctxt->fi.error_code = 0;
+
+	return ES_EXCEPTION;
+}
+
 /* Include code shared with pre-decompression boot stage */
 #include "sev-shared.c"
 
@@ -1508,6 +1535,9 @@ static enum es_result vc_handle_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 			return ES_DECODE_FAILED;
 	}
 
+	if (user_mode(ctxt->regs))
+		return ES_UNSUPPORTED;
+
 	switch (mmio) {
 	case INSN_MMIO_WRITE:
 		memcpy(ghcb->shared_buffer, reg_data, bytes);