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From: Joerg Roedel <joro@8bytes.org>
To: x86@kernel.org
Cc: Joerg Roedel <joro@8bytes.org>, Joerg Roedel <jroedel@suse.de>,
	hpa@zytor.com, Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Dan Williams <dan.j.williams@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Juergen Gross <jgross@suse.com>,
	Kees Cook <keescook@chromium.org>,
	David Rientjes <rientjes@google.com>,
	Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	virtualization@lists.linux-foundation.org
Subject: [PATCH v5 52/75] x86/sev-es: Handle MMIO String Instructions
Date: Fri, 24 Jul 2020 18:03:13 +0200	[thread overview]
Message-ID: <20200724160336.5435-53-joro@8bytes.org> (raw)
In-Reply-To: <20200724160336.5435-1-joro@8bytes.org>

From: Joerg Roedel <jroedel@suse.de>

Add handling for emulation the MOVS instruction on MMIO regions, as done
by the memcpy_toio() and memcpy_fromio() functions.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/kernel/sev-es.c | 77 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index fa1fa55fd8e3..7bfd402c74e3 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -595,6 +595,73 @@ static enum es_result vc_handle_mmio_twobyte_ops(struct ghcb *ghcb,
 	return ret;
 }
 
+/*
+ * The MOVS instruction has two memory operands, which raises the
+ * problem that it is not known whether the access to the source or the
+ * destination caused the #VC exception (and hence whether an MMIO read
+ * or write operation needs to be emulated).
+ *
+ * Instead of playing games with walking page-tables and trying to guess
+ * whether the source or destination is an MMIO range, split the move
+ * into two operations, a read and a write with only one memory operand.
+ * This will cause a nested #VC exception on the MMIO address which can
+ * then be handled.
+ *
+ * This implementation has the benefit that it also supports MOVS where
+ * source _and_ destination are MMIO regions.
+ *
+ * It will slow MOVS on MMIO down a lot, but in SEV-ES guests it is a
+ * rare operation. If it turns out to be a performance problem the split
+ * operations can be moved to memcpy_fromio() and memcpy_toio().
+ */
+static enum es_result vc_handle_mmio_movs(struct es_em_ctxt *ctxt,
+					  unsigned int bytes)
+{
+	unsigned long ds_base, es_base;
+	unsigned char *src, *dst;
+	unsigned char buffer[8];
+	enum es_result ret;
+	bool rep;
+	int off;
+
+	ds_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_DS);
+	es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
+
+	if (ds_base == -1L || es_base == -1L) {
+		ctxt->fi.vector = X86_TRAP_GP;
+		ctxt->fi.error_code = 0;
+		return ES_EXCEPTION;
+	}
+
+	src = ds_base + (unsigned char *)ctxt->regs->si;
+	dst = es_base + (unsigned char *)ctxt->regs->di;
+
+	ret = vc_read_mem(ctxt, src, buffer, bytes);
+	if (ret != ES_OK)
+		return ret;
+
+	ret = vc_write_mem(ctxt, dst, buffer, bytes);
+	if (ret != ES_OK)
+		return ret;
+
+	if (ctxt->regs->flags & X86_EFLAGS_DF)
+		off = -bytes;
+	else
+		off =  bytes;
+
+	ctxt->regs->si += off;
+	ctxt->regs->di += off;
+
+	rep = insn_has_rep_prefix(&ctxt->insn);
+	if (rep)
+		ctxt->regs->cx -= 1;
+
+	if (!rep || ctxt->regs->cx == 0)
+		return ES_OK;
+	else
+		return ES_RETRY;
+}
+
 static enum es_result vc_handle_mmio(struct ghcb *ghcb,
 				     struct es_em_ctxt *ctxt)
 {
@@ -655,6 +722,16 @@ static enum es_result vc_handle_mmio(struct ghcb *ghcb,
 		memcpy(reg_data, ghcb->shared_buffer, bytes);
 		break;
 
+		/* MOVS instruction */
+	case 0xa4:
+		bytes = 1;
+		fallthrough;
+	case 0xa5:
+		if (!bytes)
+			bytes = insn->opnd_bytes;
+
+		ret = vc_handle_mmio_movs(ctxt, bytes);
+		break;
 		/* Two-Byte Opcodes */
 	case 0x0f:
 		ret = vc_handle_mmio_twobyte_ops(ghcb, ctxt);
-- 
2.27.0


  parent reply	other threads:[~2020-07-24 16:06 UTC|newest]

Thread overview: 97+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24 16:02 [PATCH v5 00/75] x86: SEV-ES Guest Support Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 01/75] KVM: SVM: Add GHCB definitions Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 02/75] KVM: SVM: Add GHCB Accessor functions Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 03/75] KVM: SVM: Use __packed shorthand Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 04/75] x86/cpufeatures: Add SEV-ES CPU feature Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 05/75] x86/traps: Move pf error codes to <asm/trap_pf.h> Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 06/75] x86/insn: Make inat-tables.c suitable for pre-decompression code Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 07/75] x86/umip: Factor out instruction fetch Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 08/75] x86/umip: Factor out instruction decoding Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 09/75] x86/insn: Add insn_get_modrm_reg_off() Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 10/75] x86/insn: Add insn_has_rep_prefix() helper Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 11/75] x86/boot/compressed/64: Disable red-zone usage Joerg Roedel
2020-07-24 17:43   ` Kees Cook
2020-07-24 17:58   ` Arvind Sankar
2020-07-24 16:02 ` [PATCH v5 12/75] x86/boot/compressed/64: Add IDT Infrastructure Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 13/75] x86/boot/compressed/64: Rename kaslr_64.c to ident_map_64.c Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 14/75] x86/boot/compressed/64: Add page-fault handler Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 15/75] x86/boot/compressed/64: Always switch to own page-table Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 16/75] x86/boot/compressed/64: Don't pre-map memory in KASLR code Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 17/75] x86/boot/compressed/64: Change add_identity_map() to take start and end Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 18/75] x86/boot/compressed/64: Add stage1 #VC handler Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 19/75] x86/boot/compressed/64: Call set_sev_encryption_mask earlier Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 20/75] x86/boot/compressed/64: Check return value of kernel_ident_mapping_init() Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 21/75] x86/boot/compressed/64: Add set_page_en/decrypted() helpers Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 22/75] x86/boot/compressed/64: Setup GHCB Based VC Exception handler Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 23/75] x86/boot/compressed/64: Unmap GHCB page before booting the kernel Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 24/75] x86/sev-es: Add support for handling IOIO exceptions Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 25/75] x86/fpu: Move xgetbv()/xsetbv() into separate header Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 26/75] x86/sev-es: Add CPUID handling to #VC handler Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 27/75] x86/idt: Move IDT to data segment Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 28/75] x86/idt: Split idt_data setup out of set_intr_gate() Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 29/75] x86/head/64: Install startup GDT Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 30/75] x86/head/64: Setup MSR_GS_BASE before calling into C code Joerg Roedel
2020-07-24 17:42   ` Kees Cook
2020-07-24 16:02 ` [PATCH v5 31/75] x86/head/64: Load GDT after switch to virtual addresses Joerg Roedel
2020-07-24 17:40   ` Kees Cook
2020-07-24 16:02 ` [PATCH v5 32/75] x86/head/64: Load segment registers earlier Joerg Roedel
2020-07-24 17:42   ` Kees Cook
2020-07-24 16:02 ` [PATCH v5 33/75] x86/head/64: Switch to initial stack earlier Joerg Roedel
2020-07-24 17:43   ` Kees Cook
2020-07-24 16:02 ` [PATCH v5 34/75] x86/head/64: Make fixup_pointer() static inline Joerg Roedel
2020-07-24 17:52   ` Kees Cook
2020-07-24 16:02 ` [PATCH v5 35/75] x86/head/64: Load IDT earlier Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 36/75] x86/head/64: Move early exception dispatch to C code Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 37/75] x86/head/64: Set CR4.FSGSBASE early Joerg Roedel
2020-07-24 16:02 ` [PATCH v5 38/75] x86/sev-es: Add SEV-ES Feature Detection Joerg Roedel
2020-07-24 17:54   ` Kees Cook
2020-07-24 16:03 ` [PATCH v5 39/75] x86/sev-es: Print SEV-ES info into kernel log Joerg Roedel
2020-07-24 17:54   ` Kees Cook
2020-07-24 16:03 ` [PATCH v5 40/75] x86/sev-es: Compile early handler code into kernel image Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 41/75] x86/sev-es: Setup early #VC handler Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 42/75] x86/sev-es: Setup GHCB based boot " Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 43/75] x86/sev-es: Setup per-cpu GHCBs for the runtime handler Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 44/75] x86/sev-es: Allocate and Map IST stack for #VC handler Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 45/75] x86/sev-es: Adjust #VC IST Stack on entering NMI handler Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 46/75] x86/dumpstack/64: Add noinstr version of get_stack_info() Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 47/75] x86/entry/64: Add entry code for #VC handler Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 48/75] x86/sev-es: Add Runtime #VC Exception Handler Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 49/75] x86/sev-es: Wire up existing #VC exit-code handlers Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 50/75] x86/sev-es: Handle instruction fetches from user-space Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 51/75] x86/sev-es: Handle MMIO events Joerg Roedel
2020-07-24 16:03 ` Joerg Roedel [this message]
2020-07-24 16:03 ` [PATCH v5 53/75] x86/sev-es: Handle MSR events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 54/75] x86/sev-es: Handle DR7 read/write events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 55/75] x86/sev-es: Handle WBINVD Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 56/75] x86/sev-es: Handle RDTSC(P) Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 57/75] x86/sev-es: Handle RDPMC Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 58/75] x86/sev-es: Handle INVD Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 59/75] x86/sev-es: Handle MONITOR/MONITORX Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 60/75] x86/sev-es: Handle MWAIT/MWAITX Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 61/75] x86/sev-es: Handle VMMCALL Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 62/75] x86/sev-es: Handle #AC Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 63/75] x86/sev-es: Handle #DB Events Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 64/75] x86/paravirt: Allow hypervisor specific VMMCALL handling under SEV-ES Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 65/75] x86/kvm: Add KVM " Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 66/75] x86/vmware: Add VMware specific handling for VMMCALL " Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 67/75] x86/realmode: Add SEV-ES specific trampoline entry point Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 68/75] x86/realmode: Setup AP jump table Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 69/75] x86/smpboot: Setup TSS for starting AP Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 70/75] x86/head/64: Don't call verify_cpu() on starting APs Joerg Roedel
2020-07-24 17:57   ` Kees Cook
2020-07-24 16:03 ` [PATCH v5 71/75] x86/head/64: Rename start_cpu0 Joerg Roedel
2020-07-24 17:56   ` Kees Cook
2020-07-24 16:03 ` [PATCH v5 72/75] x86/sev-es: Support CPU offline/online Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 73/75] x86/sev-es: Handle NMI State Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 74/75] x86/efi: Add GHCB mappings when SEV-ES is active Joerg Roedel
2020-07-24 16:03 ` [PATCH v5 75/75] x86/sev-es: Check required CPU features for SEV-ES Joerg Roedel
2020-07-24 17:55   ` Kees Cook
2020-07-30  1:27 ` [PATCH v5 00/75] x86: SEV-ES Guest Support Mike Stunes
2020-07-30 12:26   ` Joerg Roedel
2020-07-30 23:23     ` Mike Stunes
2020-08-18 15:07       ` Joerg Roedel
2020-08-20  0:58         ` Mike Stunes
2020-08-20 12:10           ` Joerg Roedel
2020-08-21  8:05           ` Joerg Roedel
2020-08-21 17:42             ` Mike Stunes
2020-08-22 16:30               ` Joerg Roedel

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