From: Tom Lendacky <thomas.lenda...@amd.com>

Implement a handler for #VC exceptions caused by RDMSR/WRMSR
instructions.

Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
[ jroe...@suse.de: Adapt to #VC handling infrastructure ]
Co-developed-by: Joerg Roedel <jroe...@suse.de>
Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 arch/x86/kernel/sev-es.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 84b5b8f7897a..b27d5b0a8ae1 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -134,6 +134,35 @@ static phys_addr_t es_slow_virt_to_phys(struct ghcb *ghcb, 
long vaddr)
 /* Include code shared with pre-decompression boot stage */
 #include "sev-es-shared.c"
 
+static enum es_result handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+       struct pt_regs *regs = ctxt->regs;
+       enum es_result ret;
+       bool write;
+       u64 exit_info_1;
+
+       write = (ctxt->insn.opcode.bytes[1] == 0x30);
+
+       ghcb_set_rcx(ghcb, regs->cx);
+       if (write) {
+               ghcb_set_rax(ghcb, regs->ax);
+               ghcb_set_rdx(ghcb, regs->dx);
+               exit_info_1 = 1;
+       } else {
+               exit_info_1 = 0;
+       }
+
+       ret = ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0);
+       if (ret != ES_OK)
+               return ret;
+       else if (!write) {
+               regs->ax = ghcb->save.rax;
+               regs->dx = ghcb->save.rdx;
+       }
+
+       return ret;
+}
+
 /*
  * This function runs on the first #VC exception after the kernel
  * switched to virtual addresses.
@@ -196,6 +225,9 @@ static enum es_result handle_vc_exception(struct es_em_ctxt 
*ctxt,
        case SVM_EXIT_IOIO:
                result = handle_ioio(ghcb, ctxt);
                break;
+       case SVM_EXIT_MSR:
+               result = handle_msr(ghcb, ctxt);
+               break;
        case SVM_EXIT_NPF:
                result = handle_mmio(ghcb, ctxt);
                break;
-- 
2.17.1

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