From 322ec7c89f6640ee2a99d1040b6f786cf04872cf Mon Sep 17 00:00:00 2001 From: =?utf8?q?Roger=20Pau=20Monn=C3=A9?= Date: Tue, 15 Sep 2020 12:42:58 +0200 Subject: [PATCH] x86/pv: disallow access to unknown MSRs MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Change the catch-all behavior for MSR not explicitly handled. Instead of allow full read-access to the MSR space and silently dropping writes return an exception when the MSR is not explicitly handled. Signed-off-by: Roger Pau Monné Acked-by: Andrew Cooper --- xen/arch/x86/pv/emul-priv-op.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c index c6fbf8f92d..d793eed401 100644 --- a/xen/arch/x86/pv/emul-priv-op.c +++ b/xen/arch/x86/pv/emul-priv-op.c @@ -988,9 +988,10 @@ static int read_msr(unsigned int reg, uint64_t *val, } /* fall through */ default: + gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", reg); + break; + normal: - /* Everyone can read the MSR space. */ - /* gdprintk(XENLOG_WARNING, "Domain attempted RDMSR %08x\n", reg); */ if ( rdmsr_safe(reg, *val) ) break; return X86EMUL_OKAY; @@ -1155,14 +1156,15 @@ static int write_msr(unsigned int reg, uint64_t val, } /* fall through */ default: - if ( rdmsr_safe(reg, temp) ) - break; + gdprintk(XENLOG_WARNING, + "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n", + reg, val); + break; - if ( val != temp ) invalid: - gdprintk(XENLOG_WARNING, - "Domain attempted WRMSR %08x from 0x%016"PRIx64" to 0x%016"PRIx64"\n", - reg, temp, val); + gdprintk(XENLOG_WARNING, + "Domain attempted WRMSR 0x%08x from 0x%016"PRIx64" to 0x%016"PRIx64"\n", + reg, temp, val); return X86EMUL_OKAY; } -- 2.39.5