[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.9] x86/hvm: fix interaction between internal and external emulation
commit 09d7c30f037497cea00f79cb9e7a731d4f1ef360 Author: Paul Durrant <paul.durrant@xxxxxxxxxx> AuthorDate: Wed Dec 20 15:54:39 2017 +0100 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Wed Dec 20 15:54:39 2017 +0100 x86/hvm: fix interaction between internal and external emulation A call to handle_hvm_io_completion() is needed for completing I/O that requires external emulation. Such completion should be requested when hvm_vcpu_io_need_completion() returns true after hvm_emulate_once() has completed. This is indicative of the underlying I/O emulation having returned X86EMUL_RETRY and hence a re-emulation of the instruction is needed to pick up the result of the I/O. A call to handle_hvm_io_completion() is NOT needed when the underlying I/O has not returned X86EMUL_RETRY since there will be no result to pick up. Hence it bogus to request such completion when mmio_retry is set, since this can only happen if the underlying I/O emulation has returned X86EMUL_OKAY (meaning the I/O has completed successfully). Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> # Commit 5fcb26e69e8089e20c9168774bee681b8f5a3187 # Date 2017-12-06 12:50:23 +0100 # Author Jan Beulich <jbeulich@xxxxxxxx> # Committer Jan Beulich <jbeulich@xxxxxxxx> x86/HVM: don't retain emulated insn cache when exiting back to guest vio->mmio_retry is being set when a repeated string insn is being split up. In that case we'll exit to the guest, expecting immediate re-entry. Interruptions, however, may be serviced by the guest before re-entry from the repeated string insn. Any emulation needed in the course of handling the interruption must not fetch from the internally maintained cache. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx> master commit: 9c9384d6d8184ca6d21975ccf4e4f72b560540cc master date: 2017-12-01 18:09:48 +0000 master commit: 5fcb26e69e8089e20c9168774bee681b8f5a3187 master date: 2017-12-06 12:50:23 +0100 --- xen/arch/x86/hvm/emulate.c | 18 ++++++++++-------- xen/arch/x86/hvm/io.c | 2 +- xen/arch/x86/hvm/vmx/realmode.c | 2 +- 3 files changed, 12 insertions(+), 10 deletions(-) diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c index 9e63614..9ce5ae0 100644 --- a/xen/arch/x86/hvm/emulate.c +++ b/xen/arch/x86/hvm/emulate.c @@ -1951,20 +1951,22 @@ static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt, vio->mmio_retry = 0; - rc = x86_emulate(&hvmemul_ctxt->ctxt, ops); - - if ( rc == X86EMUL_OKAY && vio->mmio_retry ) - rc = X86EMUL_RETRY; - if ( rc != X86EMUL_RETRY ) + switch ( rc = x86_emulate(&hvmemul_ctxt->ctxt, ops) ) { + case X86EMUL_OKAY: + if ( vio->mmio_retry ) + rc = X86EMUL_RETRY; + /* fall through */ + default: vio->mmio_cache_count = 0; vio->mmio_insn_bytes = 0; - } - else - { + break; + + case X86EMUL_RETRY: BUILD_BUG_ON(sizeof(vio->mmio_insn) < sizeof(hvmemul_ctxt->insn_buf)); vio->mmio_insn_bytes = hvmemul_ctxt->insn_buf_bytes; memcpy(vio->mmio_insn, hvmemul_ctxt->insn_buf, vio->mmio_insn_bytes); + break; } if ( hvmemul_ctxt->ctxt.retire.singlestep ) diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c index 214ab30..05c1479 100644 --- a/xen/arch/x86/hvm/io.c +++ b/xen/arch/x86/hvm/io.c @@ -88,7 +88,7 @@ bool hvm_emulate_one_insn(hvm_emulate_validate_t *validate, const char *descr) rc = hvm_emulate_one(&ctxt); - if ( hvm_vcpu_io_need_completion(vio) || vio->mmio_retry ) + if ( hvm_vcpu_io_need_completion(vio) ) vio->io_completion = HVMIO_mmio_completion; else vio->mmio_access = (struct npfec){}; diff --git a/xen/arch/x86/hvm/vmx/realmode.c b/xen/arch/x86/hvm/vmx/realmode.c index 1996b1f..5177a9f 100644 --- a/xen/arch/x86/hvm/vmx/realmode.c +++ b/xen/arch/x86/hvm/vmx/realmode.c @@ -103,7 +103,7 @@ void vmx_realmode_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt) rc = hvm_emulate_one(hvmemul_ctxt); - if ( hvm_vcpu_io_need_completion(vio) || vio->mmio_retry ) + if ( hvm_vcpu_io_need_completion(vio) ) vio->io_completion = HVMIO_realmode_completion; if ( rc == X86EMUL_UNHANDLEABLE ) -- generated by git-patchbot for /home/xen/git/xen.git#stable-4.9 _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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