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Thu, 07 Jan 2021 20:35:08 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 046297dd-aae7-4367-bbc6-18123069346c DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2020-01-29; bh=Bhn1XpcYtMjdOpy5EowmGrcJmomV82yzTHtsIJQu40A=; b=LNkPhjN/1mKq6dcW9CcPaSO7HXu8CtViKdQ9RgoO9FhFnEGnTw5eCvYCvQFCFsbnyfRs /r2JBsJleBpbknC1KwZxNnOoech2/uVnR6mGHBMmSFIBdHQBah+Ut6kVvLlUSm0PKJ8l wIThNXauAPWMMUbmN6SVilTI2e4dT06Sqyq/YBeMt5rKtR7yG+JJW+Mk5wC97XT+PhzB 0liLoxp78FJvIaL/Nh2kMb9yng0xeUK0N03gFDk3KxZI3Oc/iKW8I8ABt8WOcYljoHR0 BbwBUSPU5L6zGh4AN+4hFT1o1pgJjFGjiZ2N8LZLYKhWel9Dxg3rCkXL9MjEjgJbGWuA ew== From: Boris Ostrovsky To: xen-devel@lists.xenproject.org Cc: iwj@xenproject.org, wl@xen.org, anthony.perard@citrix.com, jbeulich@suse.com, andrew.cooper3@citrix.com, roger.pau@citrix.com, jun.nakajima@intel.com, kevin.tian@intel.com, boris.ostrvsky@oracle.com Subject: [PATCH 3/4] x86: Allow non-faulting accesses to non-emulated MSRs if policy permits this Date: Thu, 7 Jan 2021 15:34:57 -0500 Message-Id: <1610051698-23675-4-git-send-email-boris.ostrovsky@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1610051698-23675-1-git-send-email-boris.ostrovsky@oracle.com> References: <1610051698-23675-1-git-send-email-boris.ostrovsky@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9857 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 malwarescore=0 mlxscore=0 spamscore=0 mlxlogscore=999 phishscore=0 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101070120 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9857 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 bulkscore=0 clxscore=1015 spamscore=0 impostorscore=0 priorityscore=1501 mlxscore=0 adultscore=0 mlxlogscore=999 lowpriorityscore=0 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101070120 Starting with commit 84e848fd7a16 ("x86/hvm: disallow access to unknown MSRs") accesses to unhandled MSRs result in #GP sent to the guest. This caused a regression for Solaris who tries to acccess MSR_RAPL_POWER_UNIT and (unlike, for example, Linux) does not catch exceptions when accessing MSRs that potentially may not be present. Instead of special-casing RAPL registers we decide what to do when any non-emulated MSR is accessed based on ignore_msrs field of msr_policy. Signed-off-by: Boris Ostrovsky --- xen/arch/x86/hvm/svm/svm.c | 10 ++++------ xen/arch/x86/hvm/vmx/vmx.c | 10 ++++------ xen/arch/x86/msr.c | 20 ++++++++++++++++++++ xen/arch/x86/pv/emul-priv-op.c | 8 ++++---- xen/include/asm-x86/msr.h | 3 ++- 5 files changed, 34 insertions(+), 17 deletions(-) diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c index b819897a4a9f..c9a93448f071 100644 --- a/xen/arch/x86/hvm/svm/svm.c +++ b/xen/arch/x86/hvm/svm/svm.c @@ -1965,8 +1965,8 @@ static int svm_msr_read_intercept(unsigned int msr, uint64_t *msr_content) break; default: - gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", msr); - goto gpf; + if ( guest_unhandled_msr(v, msr, msr_content, false) ) + goto gpf; } HVM_DBG_LOG(DBG_LEVEL_MSR, "returns: ecx=%x, msr_value=%"PRIx64, @@ -2151,10 +2151,8 @@ static int svm_msr_write_intercept(unsigned int msr, uint64_t msr_content) break; default: - gdprintk(XENLOG_WARNING, - "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n", - msr, msr_content); - goto gpf; + if ( guest_unhandled_msr(v, msr, &msr_content, true) ) + goto gpf; } return X86EMUL_OKAY; diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 2d4475ee3de2..34524c7a6f00 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -3017,8 +3017,8 @@ static int vmx_msr_read_intercept(unsigned int msr, uint64_t *msr_content) break; } - gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", msr); - goto gp_fault; + if ( guest_unhandled_msr(curr, msr, msr_content, false) ) + goto gp_fault; } done: @@ -3319,10 +3319,8 @@ static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content) is_last_branch_msr(msr) ) break; - gdprintk(XENLOG_WARNING, - "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n", - msr, msr_content); - goto gp_fault; + if ( guest_unhandled_msr(v, msr, &msr_content, true) ) + goto gp_fault; } return X86EMUL_OKAY; diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c index be8e36386250..e624fc8694bf 100644 --- a/xen/arch/x86/msr.c +++ b/xen/arch/x86/msr.c @@ -164,6 +164,26 @@ int init_vcpu_msr_policy(struct vcpu *v) return 0; } +/* Returns true if policy requires #GP to the guest. */ +bool guest_unhandled_msr(const struct vcpu *v, uint32_t msr, + uint64_t *val, bool is_write) +{ + const struct msr_policy *mp = v->domain->arch.msr; + + if ( unlikely(mp->ignore_msrs != MSR_UNHANDLED_NEVER) && !is_write ) + *val = 0; + + if ( likely(mp->ignore_msrs != MSR_UNHANDLED_SILENT) ) { + if ( is_write ) + gdprintk(XENLOG_WARNING, "WRMSR 0x%08x val 0x%016"PRIx64 + " unimplemented\n", msr, *val); + else + gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", msr); + } + + return (mp->ignore_msrs == MSR_UNHANDLED_NEVER); +} + int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val) { const struct vcpu *curr = current; diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c index dbceed8a05fd..96d90eb30adc 100644 --- a/xen/arch/x86/pv/emul-priv-op.c +++ b/xen/arch/x86/pv/emul-priv-op.c @@ -984,7 +984,8 @@ static int read_msr(unsigned int reg, uint64_t *val, } /* fall through */ default: - gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", reg); + if ( !guest_unhandled_msr(curr, reg, val, false) ) + return X86EMUL_OKAY; break; normal: @@ -1146,9 +1147,8 @@ static int write_msr(unsigned int reg, uint64_t val, } /* fall through */ default: - gdprintk(XENLOG_WARNING, - "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n", - reg, val); + if ( !guest_unhandled_msr(curr, reg, &val, true) ) + return X86EMUL_OKAY; break; invalid: diff --git a/xen/include/asm-x86/msr.h b/xen/include/asm-x86/msr.h index 16f95e734428..43a48e1a50ce 100644 --- a/xen/include/asm-x86/msr.h +++ b/xen/include/asm-x86/msr.h @@ -345,5 +345,6 @@ int init_vcpu_msr_policy(struct vcpu *v); */ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val); int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val); - +bool guest_unhandled_msr(const struct vcpu *v, uint32_t msr, + uint64_t *val, bool is_write); #endif /* __ASM_MSR_H */ -- 1.8.3.1