KVM: x86: move SMM exit to a new file

Some users of KVM implement the UEFI variable store through a paravirtual
device that does not require the "SMM lockbox" component of edk2, and
would like to compile out system management mode.  In preparation for
that, move the SMM exit code out of emulate.c and into a new file.

The code is still written as a series of invocations of the emulator
callbacks, but the two exiting_smm and leave_smm callbacks are merged
into one, and all the code from em_rsm is now part of the callback.
This removes all knowledge of the format of the SMM save state area
from the emulator.  Further patches will clean up the code and
invoke KVM's own functions to access control registers, descriptor
caches, etc.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220929172016.319443-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 354 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index eea29aac83bd..5cc3efa0e21c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -30,7 +30,6 @@
 #include "tss.h"
 #include "mmu.h"
 #include "pmu.h"
-#include "smm.h"
 
 /*
  * Operand types
@@ -243,37 +242,6 @@ enum x86_transfer_type {
 	X86_TRANSFER_TASK_SWITCH,
 };
 
-static ulong reg_read(struct x86_emulate_ctxt *ctxt, unsigned nr)
-{
-	if (KVM_EMULATOR_BUG_ON(nr >= NR_EMULATOR_GPRS, ctxt))
-		nr &= NR_EMULATOR_GPRS - 1;
-
-	if (!(ctxt->regs_valid & (1 << nr))) {
-		ctxt->regs_valid |= 1 << nr;
-		ctxt->_regs[nr] = ctxt->ops->read_gpr(ctxt, nr);
-	}
-	return ctxt->_regs[nr];
-}
-
-static ulong *reg_write(struct x86_emulate_ctxt *ctxt, unsigned nr)
-{
-	if (KVM_EMULATOR_BUG_ON(nr >= NR_EMULATOR_GPRS, ctxt))
-		nr &= NR_EMULATOR_GPRS - 1;
-
-	BUILD_BUG_ON(sizeof(ctxt->regs_dirty) * BITS_PER_BYTE < NR_EMULATOR_GPRS);
-	BUILD_BUG_ON(sizeof(ctxt->regs_valid) * BITS_PER_BYTE < NR_EMULATOR_GPRS);
-
-	ctxt->regs_valid |= 1 << nr;
-	ctxt->regs_dirty |= 1 << nr;
-	return &ctxt->_regs[nr];
-}
-
-static ulong *reg_rmw(struct x86_emulate_ctxt *ctxt, unsigned nr)
-{
-	reg_read(ctxt, nr);
-	return reg_write(ctxt, nr);
-}
-
 static void writeback_registers(struct x86_emulate_ctxt *ctxt)
 {
 	unsigned long dirty = ctxt->regs_dirty;
@@ -2339,335 +2307,15 @@ static int em_lseg(struct x86_emulate_ctxt *ctxt)
 	return rc;
 }
 
-static int emulator_has_longmode(struct x86_emulate_ctxt *ctxt)
-{
-#ifdef CONFIG_X86_64
-	return ctxt->ops->guest_has_long_mode(ctxt);
-#else
-	return false;
-#endif
-}
-
-static void rsm_set_desc_flags(struct desc_struct *desc, u32 flags)
-{
-	desc->g    = (flags >> 23) & 1;
-	desc->d    = (flags >> 22) & 1;
-	desc->l    = (flags >> 21) & 1;
-	desc->avl  = (flags >> 20) & 1;
-	desc->p    = (flags >> 15) & 1;
-	desc->dpl  = (flags >> 13) & 3;
-	desc->s    = (flags >> 12) & 1;
-	desc->type = (flags >>  8) & 15;
-}
-
-static int rsm_load_seg_32(struct x86_emulate_ctxt *ctxt, const char *smstate,
-			   int n)
-{
-	struct desc_struct desc;
-	int offset;
-	u16 selector;
-
-	selector = GET_SMSTATE(u32, smstate, 0x7fa8 + n * 4);
-
-	if (n < 3)
-		offset = 0x7f84 + n * 12;
-	else
-		offset = 0x7f2c + (n - 3) * 12;
-
-	set_desc_base(&desc,      GET_SMSTATE(u32, smstate, offset + 8));
-	set_desc_limit(&desc,     GET_SMSTATE(u32, smstate, offset + 4));
-	rsm_set_desc_flags(&desc, GET_SMSTATE(u32, smstate, offset));
-	ctxt->ops->set_segment(ctxt, selector, &desc, 0, n);
-	return X86EMUL_CONTINUE;
-}
-
-#ifdef CONFIG_X86_64
-static int rsm_load_seg_64(struct x86_emulate_ctxt *ctxt, const char *smstate,
-			   int n)
-{
-	struct desc_struct desc;
-	int offset;
-	u16 selector;
-	u32 base3;
-
-	offset = 0x7e00 + n * 16;
-
-	selector =                GET_SMSTATE(u16, smstate, offset);
-	rsm_set_desc_flags(&desc, GET_SMSTATE(u16, smstate, offset + 2) << 8);
-	set_desc_limit(&desc,     GET_SMSTATE(u32, smstate, offset + 4));
-	set_desc_base(&desc,      GET_SMSTATE(u32, smstate, offset + 8));
-	base3 =                   GET_SMSTATE(u32, smstate, offset + 12);
-
-	ctxt->ops->set_segment(ctxt, selector, &desc, base3, n);
-	return X86EMUL_CONTINUE;
-}
-#endif
-
-static int rsm_enter_protected_mode(struct x86_emulate_ctxt *ctxt,
-				    u64 cr0, u64 cr3, u64 cr4)
-{
-	int bad;
-	u64 pcid;
-
-	/* In order to later set CR4.PCIDE, CR3[11:0] must be zero.  */
-	pcid = 0;
-	if (cr4 & X86_CR4_PCIDE) {
-		pcid = cr3 & 0xfff;
-		cr3 &= ~0xfff;
-	}
-
-	bad = ctxt->ops->set_cr(ctxt, 3, cr3);
-	if (bad)
-		return X86EMUL_UNHANDLEABLE;
-
-	/*
-	 * First enable PAE, long mode needs it before CR0.PG = 1 is set.
-	 * Then enable protected mode.	However, PCID cannot be enabled
-	 * if EFER.LMA=0, so set it separately.
-	 */
-	bad = ctxt->ops->set_cr(ctxt, 4, cr4 & ~X86_CR4_PCIDE);
-	if (bad)
-		return X86EMUL_UNHANDLEABLE;
-
-	bad = ctxt->ops->set_cr(ctxt, 0, cr0);
-	if (bad)
-		return X86EMUL_UNHANDLEABLE;
-
-	if (cr4 & X86_CR4_PCIDE) {
-		bad = ctxt->ops->set_cr(ctxt, 4, cr4);
-		if (bad)
-			return X86EMUL_UNHANDLEABLE;
-		if (pcid) {
-			bad = ctxt->ops->set_cr(ctxt, 3, cr3 | pcid);
-			if (bad)
-				return X86EMUL_UNHANDLEABLE;
-		}
-
-	}
-
-	return X86EMUL_CONTINUE;
-}
-
-static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
-			     const char *smstate)
-{
-	struct desc_struct desc;
-	struct desc_ptr dt;
-	u16 selector;
-	u32 val, cr0, cr3, cr4;
-	int i;
-
-	cr0 =                      GET_SMSTATE(u32, smstate, 0x7ffc);
-	cr3 =                      GET_SMSTATE(u32, smstate, 0x7ff8);
-	ctxt->eflags =             GET_SMSTATE(u32, smstate, 0x7ff4) | X86_EFLAGS_FIXED;
-	ctxt->_eip =               GET_SMSTATE(u32, smstate, 0x7ff0);
-
-	for (i = 0; i < 8; i++)
-		*reg_write(ctxt, i) = GET_SMSTATE(u32, smstate, 0x7fd0 + i * 4);
-
-	val = GET_SMSTATE(u32, smstate, 0x7fcc);
-
-	if (ctxt->ops->set_dr(ctxt, 6, val))
-		return X86EMUL_UNHANDLEABLE;
-
-	val = GET_SMSTATE(u32, smstate, 0x7fc8);
-
-	if (ctxt->ops->set_dr(ctxt, 7, val))
-		return X86EMUL_UNHANDLEABLE;
-
-	selector =                 GET_SMSTATE(u32, smstate, 0x7fc4);
-	set_desc_base(&desc,       GET_SMSTATE(u32, smstate, 0x7f64));
-	set_desc_limit(&desc,      GET_SMSTATE(u32, smstate, 0x7f60));
-	rsm_set_desc_flags(&desc,  GET_SMSTATE(u32, smstate, 0x7f5c));
-	ctxt->ops->set_segment(ctxt, selector, &desc, 0, VCPU_SREG_TR);
-
-	selector =                 GET_SMSTATE(u32, smstate, 0x7fc0);
-	set_desc_base(&desc,       GET_SMSTATE(u32, smstate, 0x7f80));
-	set_desc_limit(&desc,      GET_SMSTATE(u32, smstate, 0x7f7c));
-	rsm_set_desc_flags(&desc,  GET_SMSTATE(u32, smstate, 0x7f78));
-	ctxt->ops->set_segment(ctxt, selector, &desc, 0, VCPU_SREG_LDTR);
-
-	dt.address =               GET_SMSTATE(u32, smstate, 0x7f74);
-	dt.size =                  GET_SMSTATE(u32, smstate, 0x7f70);
-	ctxt->ops->set_gdt(ctxt, &dt);
-
-	dt.address =               GET_SMSTATE(u32, smstate, 0x7f58);
-	dt.size =                  GET_SMSTATE(u32, smstate, 0x7f54);
-	ctxt->ops->set_idt(ctxt, &dt);
-
-	for (i = 0; i < 6; i++) {
-		int r = rsm_load_seg_32(ctxt, smstate, i);
-		if (r != X86EMUL_CONTINUE)
-			return r;
-	}
-
-	cr4 = GET_SMSTATE(u32, smstate, 0x7f14);
-
-	ctxt->ops->set_smbase(ctxt, GET_SMSTATE(u32, smstate, 0x7ef8));
-
-	return rsm_enter_protected_mode(ctxt, cr0, cr3, cr4);
-}
-
-#ifdef CONFIG_X86_64
-static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
-			     const char *smstate)
-{
-	struct desc_struct desc;
-	struct desc_ptr dt;
-	u64 val, cr0, cr3, cr4;
-	u32 base3;
-	u16 selector;
-	int i, r;
-
-	for (i = 0; i < 16; i++)
-		*reg_write(ctxt, i) = GET_SMSTATE(u64, smstate, 0x7ff8 - i * 8);
-
-	ctxt->_eip   = GET_SMSTATE(u64, smstate, 0x7f78);
-	ctxt->eflags = GET_SMSTATE(u32, smstate, 0x7f70) | X86_EFLAGS_FIXED;
-
-	val = GET_SMSTATE(u64, smstate, 0x7f68);
-
-	if (ctxt->ops->set_dr(ctxt, 6, val))
-		return X86EMUL_UNHANDLEABLE;
-
-	val = GET_SMSTATE(u64, smstate, 0x7f60);
-
-	if (ctxt->ops->set_dr(ctxt, 7, val))
-		return X86EMUL_UNHANDLEABLE;
-
-	cr0 =                       GET_SMSTATE(u64, smstate, 0x7f58);
-	cr3 =                       GET_SMSTATE(u64, smstate, 0x7f50);
-	cr4 =                       GET_SMSTATE(u64, smstate, 0x7f48);
-	ctxt->ops->set_smbase(ctxt, GET_SMSTATE(u32, smstate, 0x7f00));
-	val =                       GET_SMSTATE(u64, smstate, 0x7ed0);
-
-	if (ctxt->ops->set_msr(ctxt, MSR_EFER, val & ~EFER_LMA))
-		return X86EMUL_UNHANDLEABLE;
-
-	selector =                  GET_SMSTATE(u32, smstate, 0x7e90);
-	rsm_set_desc_flags(&desc,   GET_SMSTATE(u32, smstate, 0x7e92) << 8);
-	set_desc_limit(&desc,       GET_SMSTATE(u32, smstate, 0x7e94));
-	set_desc_base(&desc,        GET_SMSTATE(u32, smstate, 0x7e98));
-	base3 =                     GET_SMSTATE(u32, smstate, 0x7e9c);
-	ctxt->ops->set_segment(ctxt, selector, &desc, base3, VCPU_SREG_TR);
-
-	dt.size =                   GET_SMSTATE(u32, smstate, 0x7e84);
-	dt.address =                GET_SMSTATE(u64, smstate, 0x7e88);
-	ctxt->ops->set_idt(ctxt, &dt);
-
-	selector =                  GET_SMSTATE(u32, smstate, 0x7e70);
-	rsm_set_desc_flags(&desc,   GET_SMSTATE(u32, smstate, 0x7e72) << 8);
-	set_desc_limit(&desc,       GET_SMSTATE(u32, smstate, 0x7e74));
-	set_desc_base(&desc,        GET_SMSTATE(u32, smstate, 0x7e78));
-	base3 =                     GET_SMSTATE(u32, smstate, 0x7e7c);
-	ctxt->ops->set_segment(ctxt, selector, &desc, base3, VCPU_SREG_LDTR);
-
-	dt.size =                   GET_SMSTATE(u32, smstate, 0x7e64);
-	dt.address =                GET_SMSTATE(u64, smstate, 0x7e68);
-	ctxt->ops->set_gdt(ctxt, &dt);
-
-	r = rsm_enter_protected_mode(ctxt, cr0, cr3, cr4);
-	if (r != X86EMUL_CONTINUE)
-		return r;
-
-	for (i = 0; i < 6; i++) {
-		r = rsm_load_seg_64(ctxt, smstate, i);
-		if (r != X86EMUL_CONTINUE)
-			return r;
-	}
-
-	return X86EMUL_CONTINUE;
-}
-#endif
-
 static int em_rsm(struct x86_emulate_ctxt *ctxt)
 {
-	unsigned long cr0, cr4, efer;
-	char buf[512];
-	u64 smbase;
-	int ret;
-
 	if ((ctxt->ops->get_hflags(ctxt) & X86EMUL_SMM_MASK) == 0)
 		return emulate_ud(ctxt);
 
-	smbase = ctxt->ops->get_smbase(ctxt);
-
-	ret = ctxt->ops->read_phys(ctxt, smbase + 0xfe00, buf, sizeof(buf));
-	if (ret != X86EMUL_CONTINUE)
-		return X86EMUL_UNHANDLEABLE;
-
-	if ((ctxt->ops->get_hflags(ctxt) & X86EMUL_SMM_INSIDE_NMI_MASK) == 0)
-		ctxt->ops->set_nmi_mask(ctxt, false);
-
-	ctxt->ops->exiting_smm(ctxt);
-
-	/*
-	 * Get back to real mode, to prepare a safe state in which to load
-	 * CR0/CR3/CR4/EFER.  It's all a bit more complicated if the vCPU
-	 * supports long mode.
-	 */
-	if (emulator_has_longmode(ctxt)) {
-		struct desc_struct cs_desc;
-
-		/* Zero CR4.PCIDE before CR0.PG.  */
-		cr4 = ctxt->ops->get_cr(ctxt, 4);
-		if (cr4 & X86_CR4_PCIDE)
-			ctxt->ops->set_cr(ctxt, 4, cr4 & ~X86_CR4_PCIDE);
-
-		/* A 32-bit code segment is required to clear EFER.LMA.  */
-		memset(&cs_desc, 0, sizeof(cs_desc));
-		cs_desc.type = 0xb;
-		cs_desc.s = cs_desc.g = cs_desc.p = 1;
-		ctxt->ops->set_segment(ctxt, 0, &cs_desc, 0, VCPU_SREG_CS);
-	}
-
-	/* For the 64-bit case, this will clear EFER.LMA.  */
-	cr0 = ctxt->ops->get_cr(ctxt, 0);
-	if (cr0 & X86_CR0_PE)
-		ctxt->ops->set_cr(ctxt, 0, cr0 & ~(X86_CR0_PG | X86_CR0_PE));
-
-	if (emulator_has_longmode(ctxt)) {
-		/* Clear CR4.PAE before clearing EFER.LME. */
-		cr4 = ctxt->ops->get_cr(ctxt, 4);
-		if (cr4 & X86_CR4_PAE)
-			ctxt->ops->set_cr(ctxt, 4, cr4 & ~X86_CR4_PAE);
-
-		/* And finally go back to 32-bit mode.  */
-		efer = 0;
-		ctxt->ops->set_msr(ctxt, MSR_EFER, efer);
-	}
-
-	/*
-	 * Give leave_smm() a chance to make ISA-specific changes to the vCPU
-	 * state (e.g. enter guest mode) before loading state from the SMM
-	 * state-save area.
-	 */
-	if (ctxt->ops->leave_smm(ctxt, buf))
-		goto emulate_shutdown;
-
-#ifdef CONFIG_X86_64
-	if (emulator_has_longmode(ctxt))
-		ret = rsm_load_state_64(ctxt, buf);
-	else
-#endif
-		ret = rsm_load_state_32(ctxt, buf);
-
-	if (ret != X86EMUL_CONTINUE)
-		goto emulate_shutdown;
+	if (ctxt->ops->leave_smm(ctxt))
+		ctxt->ops->triple_fault(ctxt);
 
-	/*
-	 * Note, the ctxt->ops callbacks are responsible for handling side
-	 * effects when writing MSRs and CRs, e.g. MMU context resets, CPUID
-	 * runtime updates, etc...  If that changes, e.g. this flow is moved
-	 * out of the emulator to make it look more like enter_smm(), then
-	 * those side effects need to be explicitly handled for both success
-	 * and shutdown.
-	 */
 	return emulator_recalc_and_set_mode(ctxt);
-
-emulate_shutdown:
-	ctxt->ops->triple_fault(ctxt);
-	return X86EMUL_CONTINUE;
 }
 
 static void